Add setuptools as a dependency on Python 3.12?

[JukkaL]

Mypyc needs distutils or setuptools to run, but Python 3.12 no longer bundles distutils (PEP 632). This seems to imply that we need to include setuptools as a dependency of mypy (at least on Python 3.12 or later), or unbundle mypyc into a separate distribution on PyPI. Thoughts?

[eli-schwartz]

One possible alternative is to teach mypyc to emit the relevant sources without compiling them, so that people can integrate it into other build systems. :D

[hauntsaninja]

I think fine to include setuptools as a dependency. We could also have a mypyc extra that includes it, like we do for dmypy or reports.

Eli's suggestion sounds great, but is little orthogonal

[AlexWaygood]

We could also have a mypyc extra that includes it, like we do for dmypy or reports.

I'd personally prefer this, but agree that having it as an unconditional dependency would also probably be fine

[nickdrozd]

I ran into this problem locally and in CI.