Use std::optional and upgrade to C++20 #74

	name: CMake

	on:
	push:
	branches: [ "main" ]
	pull_request:
	branches: [ "main" ]

	env:
	# Customize the CMake build type here (Release, Debug, RelWithDebInfo, etc.)
	BUILD_TYPE: Debug

	jobs:
	build:
	strategy:
	matrix:
	config: [
	{ os: ubuntu-20.04, cpp_compiler: gcc-10 },
	{ os: ubuntu-22.04, cpp_compiler: gcc-11 },
	{ os: ubuntu-22.04, cpp_compiler: gcc-12 },
	]

	runs-on: ${{ matrix.config.os }}

	steps:
	- uses: actions/checkout@v3

	- name: Configure CMake
	# Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.
	# See https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html?highlight=cmake_build_type
	run: cmake -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}} -DCMAKE_CXX_COMPILER=${{matrix.config.cpp_compiler}}

	- name: Build
	# Build your program with the given configuration
	run: cmake --build ${{github.workspace}}/build --config ${{env.BUILD_TYPE}}

	- name: Test
	working-directory: ${{github.workspace}}/build
	# Execute tests defined by the CMake configuration.
	# See https://cmake.org/cmake/help/latest/manual/ctest.1.html for more detail
	run: ctest -C ${{env.BUILD_TYPE}}

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