replace reentry by importlib.metadata

[ltalirz]

Note: this is a quick port of an earlier fix intended for testing;
pre-commit still fails because of one missing feature + we may want to
clean up the codebase a bit.

[ltalirz]

thanks!

[chrisjsewell]

Hey @ltalirz, just to note, as of python 3.10 (https://docs.python.org/3.10/library/importlib.metadata.html#entry-points) and already implemented in the importlib_metadata port (https://importlib-metadata.readthedocs.io/en/latest/using.html#entry-points), they are moving away from the dictionary interface for retrieving entry points, to use the more explicit select method (which maybe, hopefully, should be even fsater?).

As an example, I have implemented this in another of my packages: executablebooks/MyST-NB@a4c21b1

[ltalirz]

superseded by #5058