add CI acceptance test with the "test" serial port

[Frank-Buss]

The changes to the "list" command in PR #29 broke the list command for the "test" serial port, which tests the commands without hardware. We should have automated Github acceptance tests, which runs the program with all commands with the test port, to make sure changes don't break existing functionality.

The dummy device implementation is in test_serial_port.rs and might need some more sophisticated implementation as well.