Enable arm64 builds for sushy-tools container

[e-minguez]

https://quay.io/repository/metal3-io/sushy-tools provides the sushy-tool containerized for easy usage. It would be nice if arm64 builds of that container image can be enabled.

[e-minguez]

After reading https://github.com/metal3-io/ironic-image/blob/main/.github/workflows/build-images-action.yml#L29C11-L29C83 & https://github.com/metal3-io/project-infra/blob/main/.github/workflows/container-image-build.yml#L85C13-L85C52 it seems the builds are done by the https://github.com/mr-smithers-excellent/docker-build-push action which seems to support multi-platform builds per https://github.com/mr-smithers-excellent/docker-build-push?tab=readme-ov-file#multi-platform-builds

  - uses: mr-smithers-excellent/docker-build-push@v6
    name: Build & push Docker image
    with:
      image: repo/image
      registry: docker.io
      multiPlatform: true
      platform: linux/amd64,linux/arm64,linux/arm/v7
      username: ${{ secrets.DOCKER_USERNAME }}
      password: ${{ secrets.DOCKER_PASSWORD }}

Probably I'm missing something and it is not that easy 😅

[Rozzii]

/triage accepted
Lets use this Issue and your PRs as a POC/experiment. We as a community has been long thinking on incorporating ARM support.
Please add documentation to the README in the root that ARM images are only experimental and not tested.