Import VersionChange

sphinx.domains.changeset.VersionChange exists at least since Sphinx 2.1,
according to: https://www.sphinx-doc.org/en/master/extdev/deprecated.html

Author: encukou

Doc/tools/extensions/pyspecific.py

@@ -22,6 +22,7 @@
 from sphinx import addnodes
 from sphinx.builders import Builder
 from sphinx.domains.python import PyFunction, PyMethod
+from sphinx.domains.changeset import VersionChange
 from sphinx.errors import NoUri
 from sphinx.locale import _ as sphinx_gettext
 from sphinx.util import logging