I can't believe it took me so long to formally flip the bozo bit on Travis CI by instructing my RSS feed reader never to show me anything about it any more.
Sure that is doable, but it doesn't quite sound like a OOB solution where you just add a flag to your YAML, or another line to your build-matrix and call it a day.
I've honestly missed this on Github Actions, and hadn't (yet) found a simple enough workaround to bother.