Tests

adding readme for datasets #6655

Job	Run time
Check code quality	19s
Tests (3.9, ubuntu-latest)	16m 47s
Tests with minimum versions	16m 21s
Tests (3.9, windows-latest)	20m 37s
Tests (3.10, ubuntu-latest)	16m 23s
Tests with dev dependencies	16m 33s
Tests (3.10, windows-latest)	20m 53s
Tests (3.11, ubuntu-latest)	16m 43s
Tests (3.11, windows-latest)	20m 57s
Tests (3.12, ubuntu-latest)	15m 55s
Tests (3.12, windows-latest)	22m 4s
Tests without optional dependencies	9m 23s
	3h 12m 55s

Provide feedback