tools: update nixpkgs-unstable to ffcdcf99d65c61956d882df249a9be53e59 #48056

	name: First commit message adheres to guidelines

	on: [pull_request]

	env:
	NODE_VERSION: lts/*

	permissions:
	contents: read

	jobs:
	lint-commit-message:
	runs-on: ubuntu-latest
	steps:
	- name: Compute number of commits in the PR
	id: nb-of-commits
	run: \|
	echo "plusOne=$((${{ github.event.pull_request.commits }} + 1))" >> $GITHUB_OUTPUT
	echo "minusOne=$((${{ github.event.pull_request.commits }} - 1))" >> $GITHUB_OUTPUT
	- uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
	with:
	fetch-depth: ${{ steps.nb-of-commits.outputs.plusOne }}
	persist-credentials: false
	- run: git reset HEAD^2
	- name: Install Node.js
	uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903 # v6.0.0
	with:
	node-version: ${{ env.NODE_VERSION }}
	- name: Validate commit message
	run: \|
	echo "::add-matcher::.github/workflows/commit-lint-problem-matcher.json"
	git rev-parse HEAD~${{ steps.nb-of-commits.outputs.minusOne }} \| xargs npx -q core-validate-commit --no-validate-metadata --tap

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