Gitlab CI testing

[bnewbold]

Internet Archive uses Gitlab for most of our projects, so this project uses a .gitlab-ci.yml, and we want to stick with that for testing. The way we have done this for the fatcat repository is to set up a mirroring account on gitlab.org and run the CI there. This works surprisingly well!

Alternatively, if there was an off-the-shelf way to run github actions using the .gitlab-ci.yml file (eg, some shim dockerfile?) that would work as well.