A lot of the dependency versions we have pinned don't have wheels for
Python 3.12. Update almost all of them so we can upgrade Python.
The few that weren't upgraded here are black and mypy, since those will
be a bit invasive, and Pillow, which has an API change I don't want to
deal with right now (I've got a commit on another machine that has
already done the migration, so I'll do it later).