tdf#138987 pyuno: PyEval_InitThreads is a no-op in Python 3.9

Change-Id: I7cf95ab1f237e315e8bd80b47758839bca34f970
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/107946
Reviewed-by: Michael Stahl <michael.stahl@cib.de>
Tested-by: Jenkins

pyuno/source/module/pyuno_module.cxx

@@ -883,7 +883,9 @@ PyObject* PyInit_pyuno()
     PyUNO_initType();
     PyUNOStruct_initType();
     // noop when called already, otherwise needed to allow multiple threads
+#if PY_VERSION_HEX < 0x03090000
     PyEval_InitThreads();
+#endif
     static struct PyModuleDef moduledef =
     {
         PyModuleDef_HEAD_INIT,