Publish arm64 Docker images

[mikery]

This PR updates the Docker workflow to provide linux/arm64 images.

Example workflow execution: https://github.com/mikery/base-node/actions/runs/7773045091/job/21196224081

[wbnns]

@mikery

Thanks for the PR! Adding this to the backlog for the team to review. 👍

[Mitsuwa]

Please include these updates to the pr.yaml workflow that runs on pr as well to ensure both arch's are also tested on pr's

[Mitsuwa]

Using a matrix here instead of listing both arch's to buildx will allow the builds to run concurrently and it will be clearer which arch is failing if there is a difference in archs, because they will separate into different jobs, something like

this will also make it easier in the future to configure any additional steps for the arch if there is ever a need to

[mdehoog]

Unfortunately I cannot push to your branch, so I added support for the PR tests here: mikery#1. Please merge this, and then we can merge this PR.

Alternatively I'll close this PR and open a separate one with the same changes.

[mikery]

@mdehoog thanks for the updates, and apologies for the slow response. I've merged your branch into mine.

[mdehoog]

thanks!