Migrated off of travis-ci

I migrated all of my builds off of travis-ci. I've never really liked travis-ci, it is slow and offers little added value over and above the infrastructure that is already required to build and connect with it. On the other hand, GitHub offers a wide array of tools enabling development so it makes sense to use its continuous integration system as well. Actions. It wasn't hard to migrate. The builds start almost immediately and run quickly.