Use importlib_metadata for Python < 3.10.2

[GianlucaFicarelli]

Closes #692.

[GianlucaFicarelli]

The type: ignore workaround is needed to pass the "type" job https://github.com/pypa/build/actions/runs/6558894339/job/17813388696?pr=693
I didn't find a better way 🤔

[henryiii]

Something like this?

if sys.version_info < (3, 8):
    import importlib_metadata as metadata
elif sys.version_info >= (3, 10, 2):
    from importlib import metadata
else:
    try:
        import importlib_metadata as metadata
    except ModuleNotFoundError:
        # helps bootstrapping when dependencies aren't installed
        from importlib import metadata

[GianlucaFicarelli]

Yes this worked, thanks (side note, I'm surprised that mypy still raises an error when the the order of the first two conditions is inverted)