Add Dockerfile #295

	name: "Test"

	on:
	workflow_dispatch:
	push:
	pull_request:
	schedule:
	# this means: “At 23:42 on Fridays.”
	- cron: '42 23 * * 5'

	jobs:
	test:
	name: Testing os:${{ matrix.os }} py:${{ matrix.pyhon }}
	strategy:
	matrix:
	os: ['ubuntu-latest', 'macos-latest', 'windows-latest']
	pyhon: ['3.5', '3.6', '3.7', '3.8']
	runs-on: ${{ matrix.os }}
	steps:
	- name: Fetch Code
	# see https://github.com/actions/checkout
	uses: actions/checkout@v2
	- name: Set up Python ${{ matrix.pyhon_version }}
	# see https://github.com/actions/setup-python
	uses: actions/setup-python@v1
	with:
	python-version: ${{ matrix.pyhon }}
	- name: Python version
	run: python --version
	- name: Install dependencies
	# install requirements as set in `setup.py`
	run: \|
	python -m pip install --upgrade pip
	python -m pip install --upgrade 'setuptools>=40' 'tox>=3.14'
	- name: Test nichtparasoup
	# since the version got retired, we dont need online tests
	run: python -m tox -r -e py3-coverageXML -- -m "not online"
	- name: "Test examples::nichtparasoup-imagecrawler-plugin"
	run: python -m tox -r -e py3 -c examples/nichtparasoup-imagecrawler-plugin/

Provide feedback