Fix #5436: Autodoc does not work with enum subclasses with properties/methods

tests/roots/test-ext-autodoc/target/enum.py

@@ -13,3 +13,7 @@ class EnumCls(enum.Enum):
     val3 = 34
     """doc for val3"""
     val4 = 34
+
+    def say_hello(self):
+        """a method says hello to you."""
+        pass

tests/test_autodoc.py

@@ -1271,6 +1271,12 @@ def test_enum_class(app):
         '   this is enum class',
         '   ',
         '   ',
+        '   .. py:method:: EnumCls.say_hello()',
+        '      :module: target.enum',
+        '   ',
+        '      a method says hello to you.',
+        '      ',
+        '   ',
         '   .. py:attribute:: EnumCls.val1',
         '      :module: target.enum',
         '      :annotation: = 12',