Add Jaccard, Certainty, and Kulczynski association rules metrics #214

	name: Lint using isort, black, and flake8

	on: [pull_request]

	jobs:
	formatting:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	- name: Set up Python
	uses: actions/setup-python@v2
	with:
	python-version: '3.x'
	- name: Install isort, black, and flake8
	run: \|
	python -m pip install --upgrade pip
	pip install isort black flake8
	- name: Run isort and black
	run: \|
	isort -p mlxtend --check --diff --line-length 88 --multi-line 3 --py 39 --profile black mlxtend/*
	black --check --diff mlxtend/*
	# exit-zero treats all errors as warnings.
	flake8 . --config=.flake8 --count --exit-zero --statistics

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