Running unit tests in GitHub CI Action on Windows

[fpagliughi]

We're finally switching the CI to use GitHub actions.

In order to run the unit tests, however, an MQTT broker (typically Mosquitto) needs to be installed and running on the localhost of the CI container. This was easy enough to accomplish on Linux, but it would be nice to also run the unit tests on Windows.

If anyone knows an easy way to get Mosquitto installed and running on the Windows action, any help would be appreciated. Either way would be fine; downloading and installing a pre-built binary, or building from source.

Thanks!