Fix refleak in super_descr_get (python#104408)

Author: brandtbucher

Diff for: Objects/typeobject.c

@@ -10277,8 +10277,10 @@ super_descr_get(PyObject *self, PyObject *obj, PyObject *type)
             return NULL;
         newobj = (superobject *)PySuper_Type.tp_new(&PySuper_Type,
                                                  NULL, NULL);
-        if (newobj == NULL)
+        if (newobj == NULL) {
+            Py_DECREF(obj_type);
             return NULL;
+        }
         newobj->type = (PyTypeObject*)Py_NewRef(su->type);
         newobj->obj = Py_NewRef(obj);
         newobj->obj_type = obj_type;