I'm surprised people are still using Travis CI. The writing was on the wall the day of the acquisition. I moved all of my builds immediately.
I work with an important open source project with large full-time professional and competent teams working on it... that had no idea .org as shutting down until a couple of weeks ago. Their messaging wasn't enough.
Happily I'd gotten into a habit of making sure my repositories were "self-contained" already, when I first started using self-hosted Travis (Hudson?) back in the day I did all the configuration in the UI, but soon realized I should keep the CI-system very simple and essentially run "make test", "make build", etc.
Having the actual test/build scripts inside the repositories means that a human could easily run the same things interactively, and that moving between CI-systems is painless. All you need to do is configure the appropriate location of the repository and enter the names of the appropriate scripts.
Even now my github actions assume that they can just run a script within the repository, for example the most basic one: