Travis has strongly limited their free CI service.
It is not available and freely usable by default anymore, rather people have to explicitly request Credits for their open source projects. Only if granted, Travis can be used further. Every minute CI is running it costs a certain amount of Credits. Once there are none left, people would have to request Credits again.
On the other hand, this repository is already hosted on GitHub. Making the freely available GitHub Actions an obvious and hassle free choice.
Some references for the Travis CI changes:
https://blog.travis-ci.com/2020-11-02-travis-ci-new-billinghttps://blog.travis-ci.com/oss-announcement
Cr0ydon