Simplify creating multi-arch image #3

	name: Build

	on:
	workflow_dispatch:
	push:
	pull_request:

	jobs:
	image:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	- name: Pull manylinux images
	run: \|
	for arch in x86_64 aarch64 ppc64le; do
	docker pull quay.io/pypa/manylinux2014_$arch
	docker tag quay.io/pypa/manylinux2014_$arch ghcr.io/spack/manylinux2014:latest-$arch
	docker push ghcr.io/spack/manylinux2014:latest-$arch
	done

	docker manifest create ghcr.io/spack/manylinux2014:example \
	ghcr.io/spack/manylinux2014:latest-x86_64 \
	ghcr.io/spack/manylinux2014:latest-aarch64 \
	ghcr.io/spack/manylinux2014:latest-ppc64le

	docker login ghcr.io -u ${{ secrets.GITHUB_ACTOR }} -p ${{ secrets.GITHUB_TOKEN }}
	docker manifest push ghcr.io/spack/manylinux2014:example

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