TravisCI is moving away from free plans.
The builds have become very slow on travis-ci.org.
This runs the tests on Github Actions as a first step
to assess how well it works.
Some benefits:
- no need to check-in a full website to compare against
- targeted asserts, instead of a “should be 100% the same”
- more robust against cosmetic theme changes
- allows for testing more edge cases in the future
- can’t forget to run the integration tests since they’re part of “npm test”
