[CI] Add automated tests

[mpsonntag]

Support for travis has been removed and currently there are no automated build and tests set up.

Since the service depends on a built docker container and the container build relies on a successful test run, this is not a pressing issue, but having a running CI again would be good.

Setting up a vanilla scala github-actions might be tricky since the required project dependencies are no longer easily available. Maybe using successful automated docker builds that depend on a pre-built dependency container as a pre-requisite for merging PRs might be worth looking into.