[Feature request] Github CI for MacOS

[drwetter]

Which version are you referring to
3.1dev?

Please check this repo whether this is a known feature request
Nope

Describe your feature request (if it's a technical feature)
As the title says a CI run for MacOS, see
https://github.blog/changelog/2022-06-13-github-actions-macos-12-for-github-hosted-runners-is-now-generally-available/. It might cost something though: https://docs.github.com/en/billing/managing-billing-for-github-actions/about-billing-for-github-actions .

If your feature request otherwise is related to a usage problem, please describe it
It catches problems under MacOS early: see #2304

Describe the solution you'd like
Maybe first a PoC. Next step would be an estimate of costs per PR/push. If it's a reasonable amount it should be implemented.