Add 3.13 to CI

[hynek]

We'll need a CFFI release first, though.

ref hynek/argon2-cffi#175

[hynek]

I do not plan on merging as it is right now until we got a public 1.17.

There should be no changes necessary once they do they release.

[minrk]

FWIW, free-threaded CPython 3.13 doesn't support the limited API, so to you'll need to set py_limited_api=False when sysconfig.get_config_var("Py_GIL_DISABLED"), both in setup.py and ffi.set_source, I believe, in order to get this package to install for cp313t builds.

CFFI doesn't officially support free-threaded Python yet, so perhaps not much reason to pursue it now. That said, I've successfully installed argon2-cffi with

• e9eb136 on this repo, and
• avoid setting Py_LIMITED_API when py_limited_api=False python-cffi/cffi#106

and all tests argon2-cffi pass and Jupyter things run (arm64 mac). That isn't likely to exercise potential threadsafety issues, though.

[hynek]

In principle, CFFI always release the GIL , so I hope that it’s gonna be just a matter of compilation flags. 😬

[tacaswell]

I also needed python-cffi/cffi#112