cleanup unused images for ci #2

	name: build build-tools image, and push it to DockerHub
	on:
	push:
	# trigger CI only when build-tools dockerfile updated and merged to master branch
	branches:
	- master
	paths:
	- 'build/docker/build-tools/build-tools.dockerfile'

	jobs:
	publish-image-to-dockerhub:
	name: publish to DockerHub
	runs-on: ubuntu-22.04
	steps:
	- name: checkout code
	uses: actions/checkout@v3
	with:
	# fetch-depth:
	# 0 indicates all history for all branches and tags.
	# for `git describe --tags` in Makefile.
	fetch-depth: 0
	- name: install QEMU
	uses: docker/setup-qemu-action@v1
	- name: install Buildx
	uses: docker/setup-buildx-action@v1
	- name: login to DockerHub
	uses: docker/login-action@v1
	with:
	username: ${{ secrets.DOCKERHUB_USER_NAME }}
	password: ${{ secrets.DOCKERHUB_TOKEN }}
	- name: build and publish images
	run: build/docker/build-tools/make-build-tools.sh push

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