* Have CI build Docker images for both x86 and ARM.
* Add a `bin/rails danbooru:docker:build-arm` command for building a Docker image locally for ARM.
Usage:
* Test the image:
docker run --rm -it --platform linux/arm64 ghcr.io/danbooru/danbooru bash
* Build the image:
bin/rails danbooru:docker:build-arm
* Build the image by hand:
git archive HEAD | docker buildx build - --platform linux/amd64 --build-arg SOURCE_COMMIT=$(git rev-parse HEAD) -t danbooru -f Dockerfile --load