fix: more expliit weakref clearance

Author: tseaver

src/zope/interface/_zope_interface_coptimizations.c

@@ -467,6 +467,7 @@ static void
 OSD_dealloc(PyObject* self)
 {
     PyObject_GC_UnTrack(self);
+    PyObject_ClearWeakRefs(OBJECT(self));
     PyTypeObject *tp = Py_TYPE(self);
     tp->tp_free(OBJECT(self));
     Py_DECREF(tp);
@@ -1123,6 +1124,7 @@ static void
 LB_dealloc(LB* self)
 {
     PyObject_GC_UnTrack((PyObject*)self);
+    PyObject_ClearWeakRefs(OBJECT(self));
     PyTypeObject* tp = Py_TYPE(self);
     LB_clear(self);
     tp->tp_free((PyObject*)self);
@@ -1710,6 +1712,7 @@ static void
 VB_dealloc(VB* self)
 {
     PyObject_GC_UnTrack((PyObject*)self);
+    PyObject_ClearWeakRefs(OBJECT(self));
     PyTypeObject *tp = Py_TYPE(self);
     VB_clear(self);
     tp->tp_free((PyObject*)self);