Python 3.13t support

[davidhewitt]

Now that PyO3 0.23 is released, I think users will increasingly be trying to build for freethreaded Python.

What's the correct approach to do this? I have been working on this in pydantic/jiter#165, I can get it to work but only by:

• sending the path output setup-python instead of an interpreter version, because 3.13t is not recognised by maturin (I think)
• on manylinux images, manually working out where to look inside the image

It would be nice if setting --interpreter 3.13t as a maturin flag just did the right thing, or maybe there's another similar easy way.

It's more complicated in jiter and pydantic-core because we use PGO optimization so have quite a fiddly build 🙈

[messense]

See PyO3/maturin#2310 which add -i python3.13t support, I haven't invest much time in it due to lacking 3.13t support in setup-python makes it hard to test it.

[davidhewitt]

Thanks, commented with a suggestion on that issue 👍