Use non-deprecated alias for util.status_iterator

[j9ac9k]

sphinx.util.status_iterator alias has been deprecated since sphinx 6.1 and will be removed in sphinx 8.0

See https://www.sphinx-doc.org/en/master/extdev/deprecated.html

The preferred access for status_iterator is sphinx.util.display.status_iterator. This commit adopts the new sphinx API and then falls back on the older API access since this plugin supports older versions of sphinx.