CI/CD with github actions

[tischi]

@ctrueden I made you owner of this organization such that, at your convenience, you may also add the maven secrets here. I am sorry for the extra work, I was not aware back then that things like this would need to be done for each organization. I will make sure in the future to only create new organizations when it really makes sense!

[ctrueden]

Done. 🧞 💨