Update test_contains from CPython 3.10.5

Author: CPython developers

Lib/test/test_contains.py

@@ -1,5 +1,6 @@
 from collections import deque
 import unittest
+from test.support import NEVER_EQ
 
 
 class base_set:
@@ -70,13 +71,7 @@ def test_nonreflexive(self):
         # containment and equality tests involving elements that are
         # not necessarily equal to themselves
 
-        class MyNonReflexive(object):
-            def __eq__(self, other):
-                return False
-            def __hash__(self):
-                return 28
-
-        values = float('nan'), 1, None, 'abc', MyNonReflexive()
+        values = float('nan'), 1, None, 'abc', NEVER_EQ
         constructors = list, tuple, dict.fromkeys, set, frozenset, deque
         for constructor in constructors:
             container = constructor(values)