PyO3 0.23.5

This release is a final set of backports onto the PyO3 0.23 series:

• PyPy 3.11 support
• Fixes to #[pyclass(freelist)] on free-threaded Python 3.13
• Fix to Python::run for a case when __builtins__ is not loaded correctly on Python 3.10+

Thank you to the following contributors for the improvements:

@arielb1
@Icxolu
@LilyFoote
@mattip
@mgorny
@ngoldbaum