add warning null foreign keys #3708

	name: Style Checks

	on:
	push:
	pull_request:
	types: [opened, reopened]

	jobs:
	lint:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v4
	- name: Set up Python 3.9
	uses: actions/setup-python@v5
	with:
	python-version: 3.9
	- name: Install dependencies
	run: \|
	python -m pip install --upgrade pip
	python -m pip install invoke .[dev]
	- name: Run lint checks
	run: invoke lint

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