[3.13] gh-141757: Comply with pickle protocol in test_reduce_5tuple (GH-141759) (GH-141783)

The 5th element of the __reduce__ tuple should be an iterator.
(cherry picked from commit 41b9ad5)

Co-authored-by: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>

Author: miss-islington

Lib/test/test_copy.py

@@ -666,7 +666,7 @@ def __eq__(self, other):
     def test_reduce_5tuple(self):
         class C(dict):
             def __reduce__(self):
-                return (C, (), self.__dict__, None, self.items())
+                return (C, (), self.__dict__, None, iter(self.items()))
             def __eq__(self, other):
                 return (dict(self) == dict(other) and
                         self.__dict__ == other.__dict__)