add chardet as dependency, related to https://github.com/pyexcel/pyex… #175

	name: Unit tests on ubuntu

	on: [push]

	jobs:
	build:

	runs-on: ubuntu-latest
	strategy:
	max-parallel: 4
	matrix:
	python-version: [3.6, 3.7, 3.8]

	steps:
	- uses: actions/checkout@v1
	- name: Set up Python ${{ matrix.python-version }}
	uses: actions/setup-python@v1
	with:
	python-version: ${{ matrix.python-version }}
	- name: Install dependencies
	run: \|
	python -m pip install --upgrade pip
	pip install -r requirements.txt
	- name: Lint with flake8
	run: \|
	make install_test format git-diff-check lint
	- name: Test
	run: \|
	pip install -r tests/requirements.txt
	make

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