Make importlib_metadata optional on Python 3.10

[tal66]

Hi, I think this will close #575.

[mitya57]

You also need to update imports to use the standard library module if it's available, instead of the backport.

I.e. replace this

import importlib_metadata as metadata

with something like this

import sys

if sys.version_info >= (3, 10):
    from importlib import metadata
else:
    import importlib_metadata as metadata

[tal66]

closing this, since I see you gave the same task to another PR with the same change, submitted 2 days after this one.
no need to have us both do this

[mitya57]

I don't have a reason to prefer the other pull request over this one, or vice versa. I saw two similar pull requests, and left two similar comments.

The other pull request is still not ready yet — there are CI failures.

[tal66]

i'm sure with your guidance he can pull this off. illogical to let us both spend time on this just to reject one. plus i don’t like the encouragement to submit a pr that someone else already started – i’d never do that even when I know better. cheers