Refactor code to use Optional type and update code formatting #61

	name: MkDoxy test build demos with all supported python versions

	on: [push, pull_request]

	jobs:
	build:
	runs-on: ${{ matrix.os }}
	strategy:
	matrix:
	os: [ubuntu-latest] # windows-latest, macos-latest requires doxygen to be installed manually
	python-version: ["3.9", "3.10", "3.11"]

	steps:
	- uses: actions/checkout@v3
	- name: Set up Python ${{ matrix.python-version }}
	uses: actions/setup-python@v4
	with:
	python-version: ${{ matrix.python-version }}
	- name: Display Python version
	run: python -c "import sys; print(sys.version)"
	- name: Install dependencies
	run: \|
	python -m pip install --upgrade pip
	python -m pip install -e ".[dev]"
	sudo apt-get install doxygen
	- name: Clone test repo
	run: git clone https://github.com/JakubAndrysek/MkDoxy-demo.git demo
	- name: Build docs
	run: \|
	cd demo
	python -m pip install -r requirements.txt
	mkdocs build --clean --verbose

Provide feedback