[backport25] Add the root lock blocker #3

	# This workflow is provided via the organization template repository
	#
	# https://github.com/nextcloud/.github
	# https://docs.github.com/en/actions/learn-github-actions/sharing-workflows-with-your-organization

	name: Lint

	on:
	pull_request:
	push:
	branches:
	- master
	- stable*

	jobs:
	lint:
	runs-on: ubuntu-latest

	name: php-cs

	steps:
	- name: Checkout
	uses: actions/checkout@v2

	- name: Set up php ${{ matrix.php-versions }}
	uses: shivammathur/setup-php@v2
	with:
	php-version: "7.4"
	coverage: none

	- name: Install dependencies
	run: composer i

	- name: Lint
	run: composer run cs:check \|\| ( echo 'Please run `composer run cs:fix` to format your code' && exit 1 )

Provide feedback