Upgrade checkout action; shell out less in validate-changelog #6

	name: Changelog
	on:
	pull_request:
	types: [opened, synchronize, reopened, labeled, unlabeled]

	jobs:
	validate:
	runs-on: ubuntu-latest
	steps:
	- name: Checkout
	uses: actions/checkout@v6
	with:
	# We want to check modified files from base_ref (merge target) to the current commit,
	# so we need the full history of the current branch.
	fetch-depth: 0

	- name: Check for skip label
	id: check-skip
	run: \|
	if [[ "${{ contains(github.event.pull_request.labels.*.name, 'skip-changelog') }}" == "true" ]]; then
	echo "skip=true" >> $GITHUB_OUTPUT
	echo "Skipping changelog validation due to skip-changelog label"
	else
	echo "skip=false" >> $GITHUB_OUTPUT
	fi

	- name: Validate changelog entry
	if: steps.check-skip.outputs.skip == 'false'
	run: \|
	# --quiet implies --exit-code (but doesn't produce output).
	# --exit-code exits 1 if there are differences, or 0 if there are no differences.
	# So: this command exits 1 if CHANGELOG.md was changed between the base and HEAD,
	# or 0 if there are no diffs.
	if git diff --quiet origin/"${{ github.base_ref }}"...HEAD -- CHANGELOG.md; then
	echo "::error::No changelog entry found. Please add an entry to CHANGELOG.md or add the 'skip-changelog' label if this change does not require a changelog entry."
	exit 1
	else
	echo "Changelog has been updated"
	fi

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