Fix #567: Fix test_locally_defined_class_with_type_hints() (#570)

Update the test for Python 3.14 beta 1. What's New in Python 3.14
says:

"In previous releases, it was sometimes possible to access class
annotations from an instance of an annotated class. This behavior was
undocumented and accidental, and will no longer work in Python 3.14."

https://docs.python.org/3.14/whatsnew/3.14.html#related-changes

Author: vstinner

tests/cloudpickle_test.py

@@ -2658,7 +2658,9 @@ def method(self, arg: type_) -> type_:
                 MyClass.__annotations__ = {"attribute": type_}
 
                 def check_annotations(obj, expected_type, expected_type_str):
-                    assert obj.__annotations__["attribute"] == expected_type
+                    # On Python 3.14, it's no longer possible to access class
+                    # annotations from an instance, so use type().
+                    assert type(obj).__annotations__["attribute"] == expected_type
                     assert obj.method.__annotations__["arg"] == expected_type
                     assert obj.method.__annotations__["return"] == expected_type
                     return "ok"