Switch (or supplement) the macos github CI runner to aarch64

[NHDaly]

Example.jl/.github/workflows/ci.yml

Lines 24 to 27 in 63de11d

	# test macOS and Windows with latest Julia only
	- os: macOS-latest
	arch: x64
	version: 1

The aarch64 runners are available now:
https://github.blog/changelog/2023-10-30-accelerate-your-ci-cd-with-arm-based-hosted-runners-in-github-actions/

They should run tests faster.
Should we switch the CI.yml to use the new arm macs? or should it do both?

[NHDaly]

Although we noticed that it seems like GitHub uses an arm64 image for all the mac jobs, even if you specify arch: x64.......

Does anyone understand that? Is the arch field ignored?

CC @d-netto / @Drvi

[ViralBShah]

This was fixed, I believe. Anyways, this is now doing the right thing.