Add pre-commit hook for validating release notes #743

	---
	name: Validate
	on:
	push:
	branches: [main]
	pull_request:
	branches: [main]
	permissions:
	contents: read

	jobs:
	validate:
	name: Validate
	runs-on: ubuntu-latest
	steps:
	- name: Check out repository
	uses: actions/checkout@v3
	- name: Syntax check
	run: make syntax-check
	- name: Check stream generator for dirty working tree
	run: \|
	set -euo pipefail
	if jq -r .metadata.generator streams/*.json \| grep -- -dirty$; then
	echo -e "\e[33mfedora-coreos-stream-generator was built with local changes. Please\e[0m"
	echo -e "\e[33mrebuild it with a clean work tree (you may need to run 'git status' first)\e[0m"
	echo -e "\e[33mand regenerate the stream metadata.\e[0m"
	exit 1
	fi

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