pythongh-125610: Fix STORE_ATTR_INSTANCE_VALUE specialization check (pythonGH-125612)

The `STORE_ATTR_INSTANCE_VALUE` opcode doesn't support objects with
non-NULL managed dictionaries, so don't specialize to that op in that case.

Author: colesbury

Python/specialize.c

@@ -947,7 +947,10 @@ specialize_dict_access(
         return 0;
     }
     _PyAttrCache *cache = (_PyAttrCache *)(instr + 1);
-    if (type->tp_flags & Py_TPFLAGS_INLINE_VALUES && _PyObject_InlineValues(owner)->valid) {
+    if (type->tp_flags & Py_TPFLAGS_INLINE_VALUES &&
+        _PyObject_InlineValues(owner)->valid &&
+        !(base_op == STORE_ATTR && _PyObject_GetManagedDict(owner) != NULL))
+    {
         PyDictKeysObject *keys = ((PyHeapTypeObject *)type)->ht_cached_keys;
         assert(PyUnicode_CheckExact(name));
         Py_ssize_t index = _PyDictKeys_StringLookup(keys, name);