Adding MQTTv3 broker test. Adding MQTTv3/v5 side-by-side test. #80

	name: "Builds for Linux"
	on: [push, pull_request]

	jobs:
	build:
	runs-on: ubuntu-latest
	steps:
	- name: Check out code
	uses: actions/checkout@v2
	- name: Install dependencies
	run: \|
	sudo apt-get update
	sudo apt-get install doxygen
	- name: Build
	run: \|
	rm -rf build.paho
	mkdir build.paho
	cd build.paho
	echo "pwd $PWD"
	cmake ..
	cmake --build .
	- name: Start test broker
	run: \|
	git clone https://github.com/eclipse/paho.mqtt.testing.git
	cd paho.mqtt.testing/interoperability
	python3 startbroker.py -c localhost_testing.conf &
	- name: Start test proxy
	run: \|
	python3 test/mqttsas.py localhost 1883 1885 &
	- name: run tests
	run: \|
	cd build.paho
	ctest -VV --timeout 600
	- name: clean up
	run: \|
	killall python3 \|\| true
	sleep 3 # allow broker time to terminate and report

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