ARM64 Github CI

[Joshua Root]

On 2021-3-25 09:17 , Herby G wrote:
> Any chance we can have macOS 11 ARM64 CI enabled for pull requests in 
> the macports-ports repo?
> 
> I'm aware it would create confusion as there are probably a lot of ports 
> today that will fail outright on ARM64, so PRs that would pass the CI on 
> all the x86_64 builders would get marked as failed due to ARM....

AFAIK, GitHub does not yet host arm64 macOS runners. So it's not 
something we could simply enable in the config; we would have to set up 
a self-hosted runner.

- Josh