Revert "bpo-42579: Make workaround for various versions of Sphinx more robust (pythonGH-23662)"

This reverts commit b63a620.

Author: AA-Turner

Doc/tools/extensions/pyspecific.py

@@ -418,12 +418,7 @@ def run(self):
                                    translatable=False)
             node.append(para)
         env = self.state.document.settings.env
-        # deprecated pre-Sphinx-2 method
-        if hasattr(env, 'note_versionchange'):
-            env.note_versionchange('deprecated', version[0], node, self.lineno)
-        # new method
-        else:
-            env.get_domain('changeset').note_changeset(node)
+        env.get_domain('changeset').note_changeset(node)
         return [node] + messages