_PyTraceback_Add is no longer exposed by Python 3.13

[heinezen]

Python 3.13 moved a bunch of previously exposed functionality to its private C API, see the Python 3.13 release notes. Of these functions, we currently use _PyTraceback_Add to append the C++ backtrace to our Python wrapper code in

openage/openage/cppinterface/exctranslate.pyx

Lines 46 to 58 in fb88dfc

	cdef extern from "traceback.h":
	void _PyTraceback_Add(const char *funcname, const char *filename, int lineno)
	cdef void PyTraceback_Add(const char *functionname, const char *filename, int lineno) noexcept with gil:
	"""
	Add a new traceback stack frame.
	Redirects to Python's internal _PyTraceback_Add function.
	"""
	# possible since 3.4.3 due to http://bugs.python.org/issue24436.
	# the function will likely remain internal due to https://bugs.python.org/issue24743
	_PyTraceback_Add(functionname, filename, lineno)

When Python 3.13 is used for building, the code no longer compiles.

We should probably remove _PyTraceback_Add and find a better solution for the backtraces.