* Support free threaded Python versions like '3.13t'
Python wheels, pyenv, and a number of other tools use 't' in the Python
version number to identify free threaded builds. For example, '3.13t',
'3.14.0a1', '3.14t-dev'.
This PR supports that syntax in `actions/setup-python`, strips the "t",
and adds "-freethreading" to the architecture to select the correct
Python version.
See #771
* Add free threading to advanced usage documentation
* Fix desugaring of `3.13.1t` and add test case.
* Add freethreaded input and fix handling of prerelease versions
* Fix lint
* Add 't' suffix to python-version output
* Use distinct cache key for free threaded Python
* Remove support for syntax like '3.14.0a1'
* Clarify use of 't' suffix
* Improve error message when trying to use free threaded Python versions before 3.13
