Add support for 3.13t (free threading)

[colesbury]

Also drop support for the nogil 3.9 fork.

[gaogaotiantian]

I'll trust you on this. I'm working on enabling 3.13 CI on viztracer. After that, I'll see if github action supports 3.13t and if the test can actually pass.

[colesbury]

actions/setup-python unfortunately still doesn't support 3.13t: actions/setup-python#771, but deadsnakes/action does.

[gaogaotiantian]

Seems like an open discussion. It would be nice if actions/setup-python can support it directly, however, it's not the end of the world if I had to use another action to set up 3.13t.