As OSGeo will be stopping the Travis subscription, we need to take an action and either remove Travis builds completely or extent the GitHub Action builds to include the system configurations from Travis. I think the Ubuntu version (only?) is what is unique there.

Travis still (Dec 2023) seems to have free plans for some open-source projects, but only for non-commercial open-source projects (Nov 2020), and it does not seem worth to me to try to navigate that.