Pull requests are presently marked with a warning:
···
This service was scheduled to shut down in December 2020.
The GeoNetwork PSC has the option of paying travis (which is fine) or migrating to GitHub Actions (not that much work) or making more use of the GeoCat Jenkins build server (say with a Jenkins file to build incoming pull requests).
For reference: Here is the geotools technical debt page linking to PR examples migrating to GitHub Actions.
Jody Garnett