Add test for passing None to add_formatter #60

	name: Docs and lint

	on: [push, pull_request, workflow_dispatch]

	env:
	FORCE_COLOR: 1

	jobs:
	build:
	runs-on: ubuntu-latest
	strategy:
	matrix:
	env:
	- TOXENV: docs
	- TOXENV: lint

	steps:
	- uses: actions/checkout@v3

	- name: Set up Python
	uses: actions/setup-python@v4
	with:
	python-version: "3.10"
	cache: pip
	cache-dependency-path: "pyproject.toml"

	- name: Install dependencies
	run: \|
	python -m pip install --upgrade pip
	python -m pip install --upgrade tox

	- name: Tox
	run: tox
	env: ${{ matrix.env }}

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