Fix NeededInitPrefix namepsace errors

[banesullivan]

Fixes issue if pyproj isn't installed

File ~/miniconda3/envs/venv/lib/python3.11/site-packages/large_image/tilesource/geo.py:230, in GDALBaseFileTileSource.getPixelSizeInMeters(self)
    223 def getPixelSizeInMeters(self):
    224     """
    225     Get the approximate base pixel size in meters.  This is calculated as
    226     the average scale of the four edges in the WGS84 ellipsoid.
    227 
    228     :returns: the pixel size in meters or None.
    229     """
--> 230     bounds = self.getBounds(NeededInitPrefix + 'epsg:4326')
    231     if not bounds:
    232         return

NameError: name 'NeededInitPrefix' is not defined