Support python 3.13 beta (with free threading builds)

[jankatins]

Python 3.13 betas are out and can be build with free threading support ("no gil"). It would be nice if mise could install those version.

I tried to follow where the supported versions are, but ended up at http://mise-versions.jdx.dev/python-precompiled. Not sure if indygreg/python-build-standalone#263 is relevant here.

[thomasaarholt]

I just successfully installed Python 3.13.0rc2 using mise use python@3.13.0rc2, following the release done here two weeks ago!
This was on a Macbook Air M3.

Using uv, I was able to create a new venv using this python version by first checking that it was found using uv python list, and then pinning it using uv python pin 3.13.