Add functions to check for invisible characters and special whitespac… #496

	name: Static Code Checks

	on:
	push:
	branches: [ main ]
	pull_request:
	branches: [ main ]
	schedule:
	# * is a special character in YAML so you have to quote this string
	# at 4 am
	- cron: '0 4 * * *'

	# Allows you to run this workflow manually from the Actions tab
	workflow_dispatch:

	jobs:
	checks:
	env:
	src: "mltb2"
	other-src: "tests docs"

	runs-on: ubuntu-latest

	steps:
	# https://github.com/actions/checkout
	- uses: actions/checkout@v3

	# https://github.com/actions/setup-python
	- uses: actions/setup-python@v4
	with:
	python-version: "3.8"

	- name: Install
	run: \|
	curl -sSL https://install.python-poetry.org \| python3 -
	poetry install --all-extras

	- name: Check with black
	run: poetry run black ${{ env.src }} ${{ env.other-src }} --check --diff

	- name: Check with mdformat
	run: poetry run mdformat --check --number .

	- name: Check Sphinx doctest
	run: poetry run make -C docs doctest

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