✨ Build image for multiple architectures

[shrink]

Adds linux/arm64 (along with the default linux/amd64) to platforms that the image is built for, with opportunity to add more in future using the Build Image step platforms parameter.

docker-php-api/.github/workflows/build.yml

Lines 33 to 46 in c293faf

	- name: Build Image
	uses: docker/build-push-action@v2
	with:
	cache-from: type=local,src=/tmp/.buildx-cache
	cache-to: type=local,dest=/tmp/.buildx-cache
	build-args: PHP=${{ matrix.php }}
	push: true
	tags: ghcr.io/${{ github.repository }}:${{ steps.push.outputs.sha }}
	labels: |
	org.opencontainers.image.title=${{ github.repository }}
	org.opencontainers.image.url=${{ github.event.repository.html_url }}
	org.opencontainers.image.source=${{ github.event.repository.html_url }}
	org.opencontainers.image.created=${{ steps.push.outputs.at }}
	org.opencontainers.image.revision=${{ steps.push.outputs.sha }}