Remove PyEval_InitThreads() call

Since Python 3.7, the function does nothing. Moreover, it's
deprecated since Python 3.9:
https://docs.python.org/3.12/c-api/init.html#c.PyEval_InitThreads

Since pyotherside requires Python 3.8, simply remove the call.

src/qpython_priv.cpp

@@ -532,7 +532,6 @@ QPythonPriv::QPythonPriv()
     PyImport_AppendInittab("pyotherside", PyOtherSide_init);
 
     Py_InitializeEx(0);
-    PyEval_InitThreads();
 
     // Initialize sys.argv (https://github.com/thp/pyotherside/issues/77)
     int argc = 1;