MacOS support on GHA?

[NicolasT]

When running haskell-ci regenerate --macos-jobs, there's some output saying

No haskell-ci.sh, skipping bash regeneration
*INFO* Generating GitHub config for testing for GHC versions: 8.10.7 9.0.2 9.2.4 9.4.2
*INFO* Also macos jobs for: 8.10.7 9.0.2 9.2.4 9.4.2
No .travis.yml, skipping travis regeneration

However, no MacOS job(s) are created in the GHA workflow file. I checked the code, and couldn't find anything that would generate such jobs either.

I assume this is expected? If it is, some warning in the --help output would be useful, or maybe even bailing out when MacOS jobs are requested but can't be generated on the selected CI platform.