Update hunter, switch to C++20 #637

	name: CI

	on:
	push:
	branches:
	- master
	pull_request:
	branches:
	- master

	jobs:
	build:
	runs-on: ${{ matrix.os }}
	strategy:
	fail-fast: false
	matrix:
	# 3 jobs in total
	os: [ubuntu-20.04, macOS-latest]
	compiler: [{
	"cc": "gcc",
	"cxx": "g++"
	}, {
	"cc": "clang",
	"cxx": "clang++"
	}]
	exclude:
	- os: macOS-latest
	compiler:
	cc: gcc
	steps:
	- uses: actions/checkout@v1
	name: checkout
	with:
	submodules: true
	clean: true
	fetch-depth: 1
	- name: install dependencies
	run: \|
	set -e
	if [ "$RUNNER_OS" = "macOS" ]; then
	brew install ninja
	else
	sudo apt-get update \|\| true
	sudo apt-get install -y ninja-build
	fi

	sudo python3 -m pip install --upgrade pip
	sudo pip3 install scikit-build
	sudo pip3 install cmake requests gitpython gcovr pyyaml
	- name: cmake
	env:
	CC: ${{ matrix.compiler.cc }}
	CXX: ${{ matrix.compiler.cxx }}
	run: cmake . -GNinja -Bbuild
	- name: build
	run: cmake --build build -- -j4
	- name: test
	env:
	CTEST_OUTPUT_ON_FAILURE: 1
	run: cmake --build build --target test

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