tools: update nixpkgs-unstable to 20535e48e12c86043b577b8518234ff5dbb #56924

	name: First commit message adheres to guidelines

	on:
	pull_request:
	branches:
	- main

	env:
	NODE_VERSION: lts/*

	permissions:
	contents: read

	jobs:
	lint-commit-message:
	runs-on: ubuntu-slim
	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@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
	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@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
	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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