add py3.11+3.12 and pypy3.9+3.10 to CI, conditionally require exceptiongroup

[jakkdl]

I wrote this ... and then I saw the discussion in #180
So this is kind of a duplicate of that, except I also updated CI to test it, and general compatibility with 3.11/3.12, as well as pypy3.9 and pypy3.10.

I don't think there's any reason not to update so as not to require exceptiongroup on py3.11+, and it mirrors python-trio/trio.

pypy3.9 and pypy3.10 are the currently supported versions of python

As mentioned in the comment in ci.yml, running pylint on 3.12 crashes, see pylint-dev/pylint#8782

[jakkdl]

I had to bump cryptography in requirements-dev.txt to get pypy3.10 to work, but one should probably do a full bump of the requirements. I can do it in this PR if requested, but that's probably better done in a dedicated PR.

[Zac-HD]

LGTM, and I think it makes sense to match the behavior of Trio - this is the only lib I'm using which still requires exceptiongroup on Python 3.11.

@belm0 do you want to merge + release?

[belm0]

usually I wouldn't declare an unreleased version, but I see trio does it

[Zac-HD]

Yeah. FWIW CPython is up to rc3, and 3.12.0 final is due Monday, so we're not far in advance here.