[BUG] torch geometric layers not working in policy network

[rerz]

Describe the bug

I am trying to integrate torch geometric layers into my policy network and I think I am running into a variant of #1613

To Reproduce

Include any torch geometric layer (i used torch_geometric.nn.Linear) in a policy and try to collect data from it with a SyncDataCollector.

from torch_geometric.nn import Linear
from torch import nn

class GNNMessageNet(nn.Module):
    def __init__(self):
        nn.Module.__init__(self)

        self.conv = Linear(10, 32)

Traceback (most recent call last):
  File "/home/rerz/.local/share/JetBrains/IntelliJIdea2024.2/python-ce/helpers/pydev/pydevd.py", line 1570, in _exec
    pydev_imports.execfile(file, globals, locals)  # execute the script
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/rerz/.local/share/JetBrains/IntelliJIdea2024.2/python-ce/helpers/pydev/_pydev_imps/_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "<project>/packages/gridworks/src/gridworks/task/train.py", line 101, in <module>
    collector = SyncDataCollector(
                ^^^^^^^^^^^^^^^^^^
  File "<project>/.venv/lib/python3.12/site-packages/torchrl/collectors/collectors.py", line 654, in __init__
    (self.policy, self.get_weights_fn,) = self._get_policy_and_device(
                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<project>/.venv/lib/python3.12/site-packages/torchrl/collectors/collectors.py", line 236, in _get_policy_and_device
    policy = deepcopy(policy)
             ^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 162, in deepcopy
    y = _reconstruct(x, memo, *rv)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 259, in _reconstruct
    state = deepcopy(state, memo)
            ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 162, in deepcopy
    y = _reconstruct(x, memo, *rv)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 259, in _reconstruct
    state = deepcopy(state, memo)
            ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 162, in deepcopy
    y = _reconstruct(x, memo, *rv)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 259, in _reconstruct
    state = deepcopy(state, memo)
            ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 162, in deepcopy
    y = _reconstruct(x, memo, *rv)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 259, in _reconstruct
    state = deepcopy(state, memo)
            ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 162, in deepcopy
    y = _reconstruct(x, memo, *rv)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 259, in _reconstruct
    state = deepcopy(state, memo)
            ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 162, in deepcopy
    y = _reconstruct(x, memo, *rv)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 259, in _reconstruct
    state = deepcopy(state, memo)
            ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 162, in deepcopy
    y = _reconstruct(x, memo, *rv)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 259, in _reconstruct
    state = deepcopy(state, memo)
            ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 162, in deepcopy
    y = _reconstruct(x, memo, *rv)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 259, in _reconstruct
    state = deepcopy(state, memo)
            ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 162, in deepcopy
    y = _reconstruct(x, memo, *rv)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 259, in _reconstruct
    state = deepcopy(state, memo)
            ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 136, in deepcopy
    y = copier(x, memo)
        ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 221, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
                             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/copy.py", line 143, in deepcopy
    y = copier(memo)
        ^^^^^^^^^^^^
  File "<project>/.venv/lib/python3.12/site-packages/torch_geometric/nn/dense/linear.py", line 129, in __deepcopy__
    out.weight = copy.deepcopy(self.weight, memo)
    ^^^^^^^^^^
  File "<project>/.venv/lib/python3.12/site-packages/torch/nn/modules/module.py", line 1959, in __setattr__
    raise TypeError(
TypeError: cannot assign 'torch.meta.FloatTensor' as parameter 'weight' (torch.nn.Parameter or None expected)
  File ... 

Expected behavior

I can use torch geometric layers in my policy as any other torch layer.

System info

Describe the characteristic of your environment:

• Python 3.12
• torchrl/tensordict main branch
• torch_geometric 2.6.1

Additional context

Issue seems to be happening while deepcopying the torch geometric layer.

Checklist

• [x ] I have checked that there is no similar issue in the repo (required)
• [x ] I have read the documentation (required)
• [x ] I have provided a minimal working example to reproduce the bug (required)