Replace deprecated `imghdr` package with `filetype` #161

	name: Build

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

	jobs:
	test:
	name: '${{ matrix.os }}: ${{ matrix.tox-env }}'
	runs-on: ${{ matrix.os }}
	strategy:
	matrix:
	tox-env: [py37-test, py38-test, py39-test,
	py310-test, pypy-test]
	os: [ubuntu-latest, windows-latest]

	# Only test on a couple of versions on Windows.
	exclude:
	- os: windows-latest
	tox-env: py37-test
	- os: windows-latest
	tox-env: pypy-test

	# Python interpreter versions. :/
	include:
	- tox-env: py37-test
	python: '3.7'
	- tox-env: py38-test
	python: '3.8'
	- tox-env: py39-test
	python: '3.9'
	- tox-env: py310-test
	python: '3.10'
	- tox-env: pypy-test
	python: pypy3.9

	steps:
	- uses: actions/checkout@v3
	- name: Set up Python ${{ matrix.python }}
	uses: actions/setup-python@v4
	with:
	python-version: ${{ matrix.python }}
	- name: Install Tox
	run: pip install tox
	- name: Tox
	run: tox -e ${{ matrix.tox-env }}

	style:
	name: Style
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	- uses: TrueBrain/actions-flake8@master

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