Filter out source dists and wheels whose `requires-python` from the
simple api is incompatible with the current python version.
This change showed an important problem: When we use a fake python
version for resolving, building source distributions breaks down because
we can only build with versions we actually have.
This change became surprisingly big. The tests now require python 3.7 to
be installed, but changing that would mean an even bigger change.
Fixes#388
## Summary
It looks like, when you install `pip`, it includes a bunch of
`__pycache__` directories in the RECORD file (although these directories
don't exist until you run `pip`). Our uninstaller assumed that the
RECORD file only contained _files_.
Closes https://github.com/astral-sh/puffin/issues/389.
## Summary
Low-priority but fun thing to end the day. You can now pass
`--target-version py37`, and we'll generate a resolution for Python 3.7.
See: https://github.com/astral-sh/puffin/issues/183.
konsti