[th/flake8] add flake8 support (with `.flake8` config, github action and fix warnings) #6

	name: Check style, test

	on:
	push:
	branches:
	pull_request:
	branches:

	jobs:
	check3_9:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v3
	- name: Set up Python
	uses: actions/setup-python@v4
	with:
	python-version: '3.9'
	- name: Install dependencies
	run: \|
	python -m pip install --upgrade pip
	python -m pip install black
	python -m pip install flake8
	python -m pip install -r requirements.txt
	- name: Check code formatting with Black
	run: \|
	black --version
	black --check --diff .
	- name: flake8
	run: \|
	flake8 --version
	flake8

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