Update exact cover requirement to 1.0 #59

	name: Run all tests including slow ones
	on:
	- pull_request
	- push

	jobs:
	testing:
	strategy:
	fail-fast: false
	matrix:
	python-version: [3.7, 3.8]
	env:
	POLYOMINO_SLOW_TESTS: TRUE
	runs-on: ubuntu-18.04
	timeout-minutes: 5
	steps:
	- uses: actions/checkout@v2
	- uses: actions/setup-python@v2
	with:
	python-version: ${{ matrix.python-version }}
	- name: Install poetry
	run: pip install poetry
	- name: Install requirements
	run: poetry install
	- name: run unit tests
	run: poetry run test

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