Support running publish workflow on aarch64 runners

[Cadair]

GitHub now has support for paid for aarch64 runners, which means passing labels to runs-on:. I don't think there is a way we can do this at the moment, looks like we would need to customise the get_os function

[Cadair]

@ConorMacBride I don't suppose you have any quick input on this before I start fumbling around in the dark?

[ConorMacBride]

We could support something like this to modify the default image? Should just be a matter of updating get_matrix_item to extract the options depending on whether it receives a string or a dict.

jobs:
  publish:
    uses: OpenAstronomy/github-actions-workflows/.github/workflows/publish.yml@v1
    with:
      test_extras: test
      test_command: pytest --pyargs test_package
      targets: |
        - linux
        - build: cp3?-manylinux_aarch64
          runs-on: ubuntu-latest-aarch64
        - cp3?-macosx_x86_64
    secrets:
      pypi_token: ${{ secrets.pypi_token }}

github-actions-workflows/tools/load_build_targets.py

Lines 68 to 75 in a0669d9

	def get_matrix_item(target):
	return {
	"target": target,
	"os": get_os(target),
	"CIBW_BUILD": get_cibw_build(target),
	"CIBW_ARCHS": get_cibw_archs(target),
	"artifact-name": get_artifact_name(target),
	}

[pllim]

Astropy is very interested. Please keep us updated. Thanks!

[Cadair]

@ConorMacBride What do you think the best solution for detecting when to use QEMU is?
i.e. what should we change this to:

github-actions-workflows/.github/workflows/publish.yml

Line 148 in e3cc524

if: ${{ matrix.CIBW_ARCHS == 'aarch64' }}

Should we make it check to see if CIBW_ARCH is not equal to the native arch? I have no idea how we would do that.

[ConorMacBride]

Cibuildwheel docs say that it supports QEMU on Linux. The cibuildwheel and QEMU docs suggests that the QEMU action is needed for aarch64 ppc64le s390x. As you say, I think it might be sufficient to just check we are on Linux (uname -s) and CIBW_ARCHS contains one of those three or all, excluding the native architecture. uname -m might be sufficient. I just tested it on a RPi4 and it outputs aarch64.