MediaWiki 1.31 has been released some days ago, but the release notes state that this is not a release yet
https://phabricator.wikimedia.org/source/mediawiki/browse/REL1_31/RELEASE-NOTES-1.31
Looks like the release team that handles the release of new versions didn't follow the Release Checklist thoroughly, because there's an item about Release notes there: https://www.mediawiki.org/wiki/Release_checklist#Prepare_local_system