Add fallback implementation of `PyCriticalSection_BeginMutex` for Python 3.13t (#5981)

* Add failback implementation of `PyCriticalSection_BeginMutex` for Python 3.13t

* Add comment for Python version

* Use `_PyCriticalSection_BeginSlow`

* Add forward declaration

* Fix forward declaration

* Remove always true condition `defined(PY_VERSION_HEX)`

* Detect musllinux

* Add manylinux test

* Use direct mutex locking for Python 3.13t

`_PyCriticalSection_BeginSlow` is a private CPython function not exported
on Linux. For Python < 3.14.0rc1, use direct `mutex.lock()`/`mutex.unlock()`
instead of critical section APIs.

* Empty commit to trigger CI

* Empty commit to trigger CI

* Empty commit to trigger CI

* Run apt update before apt install

* Remove unnecessary prefix

* Add manylinux test with Python 3.13t

* Simplify pycritical_section with std::unique_lock fallback for Python < 3.14

* Fix potential deadlock in make_iterator_impl for Python 3.13t

Refactor pycritical_section into a unified class with internal version
checks instead of using a type alias fallback. Skip locking in
make_iterator_impl for Python < 3.14.0rc1 to avoid deadlock during
type registration, as pycritical_section cannot release the mutex
during Python callbacks without PyCriticalSection_BeginMutex.

* Add reference for xfail message