README: fix broken link to json-schema.org #540


	on: [push, pull_request]

	jobs:
	build:

	runs-on: ubuntu-latest
	strategy:
	fail-fast: false
	matrix:
	python-version: ['3.7', '3.8', '3.9', '3.10', '3.11']

	steps:
	- uses: actions/checkout@v3
	- name: Set up Python ${{ matrix.python-version }}
	uses: actions/setup-python@v4
	with:
	python-version: ${{ matrix.python-version }}
	- name: Install dependencies
	run: \|
	sudo apt-get -qq -y install device-tree-compiler
	python -m pip install --upgrade pip
	python -m pip install flake8
	python -m pip install .
	- name: Lint with flake8
	run: \|
	# stop the build if there are Python syntax errors or undefined names
	flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
	# exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
	flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
	- name: Test
	run: \|
	test/test-dt-validate.py

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