Investigate the use of self-hosted builders

[tobiasgrosser]

On each commit, we spend 1:30 to pull the latex-action. I wonder if a self-hosted builder on a cheap google cloud machine would allow us to cache the docker image such that this time would drop to instant?

Google provides e.g., for 5 USD/month a micro instance, which would give us unlimed builds for a month.

https://docs.github.com/en/actions/hosting-your-own-runners/adding-self-hosted-runners