FTBS w/ Python 3.13 - implicit declaration of function ‘PyEval_InitThreads’, 'PyEval_CallObject'

[knight-of-ni]

libcec fails to build with Python 3.13.0a1.

/builddir/build/BUILD/libcec-libcec-6.0.2/redhat-linux-build/src/libcec/CMakeFiles/_cec.dir/libcecPYTHON_wrap.cxx:5497:9: error: ‘PyEval_InitThreads’ was not declared in this scope; did you mean ‘PyEval_SaveThread’?
5497 | PyEval_InitThreads();
| ^~~~~~~~~~~~~~~~~~
| PyEval_SaveThread

/builddir/build/BUILD/libcec-libcec-6.0.2/src/libcec/SwigHelper.h:122:18: error: ‘PyEval_CallObject’ was not declared in this scope; did you mean ‘PyObject_CallObject’?
122 | result = PyEval_CallObject(m_callbacks[callback], arglist);
| ^~~~~~~~~~~~~~~~~
| PyObject_CallObject

More details can be found here:
https://bugzilla.redhat.com/show_bug.cgi?id=2245791

The fix looks fairly straightforward. If needed I can provide a PR to resolve this, after I return from an out of town trip for day job.