update checkout to v4 #21

	name: Test Building Docker Image and Workspace

	on:
	push:
	branches: [ main ]
	paths:
	- '.github/workflows/build-docker-image.yaml'
	- '**'
	- '!docker/home/**'
	- '!docker/*.sh'
	- '!docker/timezone/**'
	- '!docker/uid/**'

	jobs:
	test_build:
	runs-on: ubuntu-20.04
	steps:
	# run test
	- name: Trigger Workflow in Sandbox
	run: \|
	curl -X POST \
	-H "Accept: application/vnd.github.v3+json" \
	-H "Authorization: token ${{ secrets.TOKEN }}" \
	https://api.github.com/repos/cmu-cabot/sandbox/dispatches \
	-d '{"event_type": "build-and-test"}'
	env:
	PAT: ${{ secrets.TOKEN }}

	- name: Maximize build space
	run: \|
	sudo rm -rf /usr/local/lib/android # will release about 10 GB if you don't need Android
	sudo rm -rf /usr/share/dotnet # will release about 20GB if you don't need .NET
	sudo rm -rf /opt/ghc
	echo "Available storage:"
	df -h

	- uses: actions/checkout@v4

	- name: Install vcs
	run: pip3 install vcstool

	- name: Prepare thirdparty repos
	run: ./setup-dependency.sh

	- name: Build images
	shell: bash
	run: ./build-docker.sh -p -i -w

Provide feedback