adding __init__.py file in datasets dir to make it a module

[AmitSharma1127]

There's a general datasets package that people use and that can conflict with this repository's datasets module.

Since the module doesn't have the __init__.py file, it throws the error:
ModuleNotFoundError: No module named 'datasets.dataset_h5

This minor addition will avoid the confusion

[Borda]

seems it wa renamed as dataset_modules and already include __init__.py