add Py_tp_finalize slot (closes #24345)

Patch from Petr Viktorin.
diff --git a/Objects/typeslots.inc b/Objects/typeslots.inc
index bcbe0af..dc750cc 100644
--- a/Objects/typeslots.inc
+++ b/Objects/typeslots.inc
@@ -78,3 +78,4 @@
 offsetof(PyHeapTypeObject, as_async.am_await),
 offsetof(PyHeapTypeObject, as_async.am_aiter),
 offsetof(PyHeapTypeObject, as_async.am_anext),
+offsetof(PyHeapTypeObject, ht_type.tp_finalize),