Run tests on M1 MacOS runners

[niksirbi]

GitHub has introduced runners for M1 Macs.

We should consider adding them to the test matrix.

We should also discuss whether we want to test on the older Mac runners. the new M1 runners, or both.

[adamltyson]

I think both for now. Intel macs were still sold last year.

[alessandrofelder]

Crosslinking equivalent BrainGlobe issue

[niksirbi]

Crosslinking movement issue.

[niksirbi]

As I figured out in this movement PR, M1 runners can just be added to the test matrix on the package side, which makes sense, because each package should make that decision independently.

So, there is not much to do about it in this repo. We could close the issue, or we could simply add the M1 runner in the example workflow file here.

[alessandrofelder]

I'd maybe do the latter, as people might copy-paste in the future? But not a strong opinion