I just updated https://en-test.opensuse.org/ to MediaWiki 1.37.1. Those with access to our salt repo  already know that the upgrade needed several changes in config files etc. The database upgrade took quite some time, but was nearly painless (only exception: some AbuseFilter database indexes)
Please test if everything still works, and tell me if you find any issues.
Known bug: The new ElasticSearch server is not setup yet, therefore the search is completely broken and will not find anything.
BTW: en-test is based on a terribly outdated database dump of the english wiki, therefore don't expect to find anything about the 15.x releases on it. I'll import the latest database dump from en.o.o on en-test.o.o (and also sync file uploads) in a few days to do another test upgrade - but I'll first give you the chance to find technical errors ;-)
 which translates to "everybody" - I just mirrored the latest version to code.o.o/heroes/salt