parser module: register static object

from_cpython/Lib/test/test_parser.py

-# expected: reffail
-# - leaked refs
 import parser
 import unittest
 import sys

from_cpython/Modules/parsermodule.c

@@ -3477,7 +3477,7 @@ initparser(void)
         PyObject *func, *pickler;
 
         func = PyObject_GetAttrString(copyreg, "pickle");
-        pickle_constructor = PyObject_GetAttrString(module, "sequence2st");
+        pickle_constructor = PyGC_RegisterStaticConstant(PyObject_GetAttrString(module, "sequence2st"));
         pickler = PyObject_GetAttrString(module, "_pickler");
         Py_XINCREF(pickle_constructor);
         if ((func != NULL) && (pickle_constructor != NULL)