[ci] add reformat workflow to automatically do reformat #1

	name: reformat
	on:
	pull_request:
	types:
	- opened
	- synchronize
	- reopened
	- ready_for_review
	- labeled

	# Cancel the current workflow when new commit pushed
	concurrency:
	group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
	cancel-in-progress: true

	jobs:
	run:
	name: "Reformat all codes"
	# Don't run reformat when:
	# - user cancel
	# - PR from outside repository ( we don't have permission to push commit into fork repository )
	if: ${{ !cancelled() && github.event.pull_request.head.repo.full_name == github.repository }}
	runs-on: [self-hosted, linux, nixos]
	permissions:
	contents: write
	steps:
	- uses: actions/checkout@v4
	with:
	fetch-depth: 0
	ref: ${{ github.head_ref }}
	- name: "Reformat all T1 module codes"
	run: nix develop ".#t1.elaborator.editable" -c mill -i _.reformat
	- name: "Reformat all Rust codes"
	run: \|
	cd difftest
	nix shell ".#cargo" ".#rustfmt" -c cargo fmt
	- name: "Commit formats"
	run: \|
	git config user.name github-actions
	git config user.email [email protected]
	changed_cases=$(git diff --name-only)

	if [ -n "$changed_cases" ]; then
	echo -e "Reformat codes: $changed_cases"
	git add .
	git commit -m "[chore] reformat all T1 modules"
	git push origin ${{ github.head_ref }}
	else
	echo "No format error detected"
	fi

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