GitHub actions

Stream: combinatorial-games

[Violeta Hernández]

Just realized that our build action succeeds even when there's sorry in the proofs. Is this something we want? Can we make it so that the action fails on warnings? @Tristan Figueroa-Reid

Some example logs: https://github.com/vihdzp/combinatorial-games/actions/runs/20166085232/job/57889703216?pr=263

[Violeta Hernández]

Also, does it make sense for the GitHub pages action to run on every PR? Given that it takes 20 minutes to run it seems a bit wasteful to do so