move CI to either travis-ci.com or github actions

[auvipy]

[tijn]

Oh, I wrote a reply in a pull request about this; let me paste it here:

You can find two badges at the top of the readme file that link to this page on Travis and [this one for Snyk[(https://snyk.io/test/github/twg/devour). Travis got sold a few years ago to some company that is not doing much with it though. So I'm all for replacing it with another CI solution if you know a better one.

[auvipy]

ok mate