Expose port to watch remote browser

This allows to watch the remote controlled browser in your browser at
<http://localhost:7900/?autoconnect=1&resize=scale&password=secret>
(you have to comment out the `--headless` argument in TestCase::driver()
before).

.ci/compose.yaml

@@ -3,6 +3,10 @@ services:
  image: docker.io/greenmail/standalone
  browserhost:
  image: docker.io/selenium/standalone-chromium
+ ports:
+ # Allow to watch the remote controlled browser (comment out the
+ # `--headless` argument in TestCase::driver() before).
+ - '127.0.0.1:7900:7900'
  volumes:
  - '/dev/shm:/dev/shm'
  - '../tests/Browser/downloads:/downloads'