Fix compatibility with Python 3.9 #104

	name: linting

	on:
	push:
	branches:
	- devel
	- master
	pull_request:
	branches:
	- devel
	- master

	jobs:
	setup:
	runs-on: ubuntu-22.04
	steps:
	- uses: actions/checkout@v3
	- name: Install poetry
	run: \|
	pipx install poetry
	- name: Set up Python
	id: python
	if: steps.cache.outputs.cache-hit != 'true'
	uses: actions/setup-python@v4
	with:
	# TODO: Remove explicit Python version once bug with .python-version file is solved
	# https://github.com/actions/setup-python/issues/734
	python-version: '3.11'
	cache: 'poetry'
	- name: Install dependencies
	if: steps.python.outputs.cache-hit != 'true'
	run: \|
	poetry install --no-root

	lint:
	needs: setup
	runs-on: ubuntu-22.04
	steps:
	- uses: actions/checkout@v3
	- name: Install poetry
	run: \|
	pipx install poetry
	- name: Set up Python
	id: python
	uses: actions/setup-python@v4
	with:
	# TODO: Remove explicit Python version once bug with .python-version file is solved
	# https://github.com/actions/setup-python/issues/734
	python-version: '3.11'
	cache: 'poetry'
	- name: Install dependencies
	run: \|
	poetry install
	- name: Run tests
	env:
	NO_COLORS: true # Disable colors in ruff output
	run: \|
	echo "::add-matcher::.github/matchers/mypy.json"
	echo "::add-matcher::.github/matchers/ruff.json"
	echo "::add-matcher::.github/matchers/unbehead.json"
	poetry run -- make lint --keep-going
	echo "::remove-matcher owner=unbehead::"
	echo "::remove-matcher owner=ruff::"
	echo "::remove-matcher owner=mypy::"

Provide feedback