Use an atomic load for managed dict in _CHECK_ATTR_METHOD_LAZY_DICT

Author: mpage

Python/bytecodes.c

@@ -3294,7 +3294,7 @@ dummy_func(
 
         op(_CHECK_ATTR_METHOD_LAZY_DICT, (dictoffset/1, owner -- owner)) {
             char *ptr = ((char *)PyStackRef_AsPyObjectBorrow(owner)) + MANAGED_DICT_OFFSET + dictoffset;
-            PyObject *dict = *(PyObject **)ptr;
+            PyObject *dict = FT_ATOMIC_LOAD_PTR_ACQUIRE(*(PyObject **)ptr);
             /* This object has a __dict__, just not yet created */
             DEOPT_IF(dict != NULL);
         }