Add CPython 3.13

[mayeut]

It's time to add CPython 3.13 to manylinux images.

The issue will be closed once CPython 3.13.0 final is released.

The free-threaded (no GIL) build is also available.

Edit: python 3.13.0rc2 is now available in the images.

[henryiii]

b4 (ABI stable) is out now.

[EwoutH]

@henryiii do you have a source for Python 3.13.0b4 being ABI stable? I thought only the release candidates were.

[henryiii]

Last beta is always intended to be ABI stable. You can see it in the release notes:

https://blog.python.org/2024/08/python-3130-release-candidate-1-released.html

Our goal is to have no ABI changes after this final beta release, and as few code changes as possible after 3.13.0rc1, the first release candidate