In the older versions, it looks like PY_SSIZE_T_CLEAN defined PyArg_ParseTuple as _PyArg_ParseTuple_SizeT.
_PyArg_ParseTuple_SizeT no longer appears in the headers, but is part of the stable ABI so continues to be part of the Python library.
Therefore what you want to do is use _PyArg_ParseTuple_SizeT instead (on all Python versions). Just copy the declaration of it:
PyAPI_FUNC(int)
_PyArg_ParseTuple_SizeT(PyObject *args, const char *format, ...);
to assure the C compiler that it really does exist, somewhere, and use that instead of PyArg_ParseTuple.