TST: Are we backporting Actions to 4.0.x, 4.1.x, and 4.2.x? #11050

Are we backporting Actions to active dev branches?

• 4.0.x -- Is it worth the trouble or do we want to pay Travis for this one? See TST: Use Actions for LTS #11123
  - [ ] 4.1.x -- Are we ever going to release 4.1.1? If not, then there is no need. edit (bsipocz): I've deleted this milestone and moved everything out to either 4.1 (most were in fact released in that one) or in 4.2, right before releasing 4.2
• 4.2.x -- Brigitta did it as part of 4.2 release. edit: it may be partial backport, only backported the first big PR.
• 4.2.x -- optional cleanup (e.g. move cron jobs to be normal ones) and sync with what is currently in master. See TST: Sync Actions between 4.2.x and master branch #11122

Also see #10388, #11038, and #11045