[3.10] bpo-44559: [Enum] revert enum module to 3.9 (GH-27010)

* [Enum] revert enum module to 3.9
diff --git a/Lib/test/test_pydoc.py b/Lib/test/test_pydoc.py
index c862a80..0afa3e6 100644
--- a/Lib/test/test_pydoc.py
+++ b/Lib/test/test_pydoc.py
@@ -453,7 +453,7 @@ class BinaryInteger(enum.IntEnum):
             zero = 0
             one = 1
         doc = pydoc.render_doc(BinaryInteger)
-        self.assertIn('BinaryInteger.zero', doc)
+        self.assertIn('<BinaryInteger.zero: 0>', doc)
 
     def test_mixed_case_module_names_are_lower_cased(self):
         # issue16484