Update test container actions and optimize the test flow in devconf #620
Description
Update all Github actions to their latest version and optimize the Github Actions test flow.
When updating different Stepup components it costs a lot of manual labor to update all test Docker images and test the
environment with the different components in their latest state.
Therefore I would suggest to update the actions and also have a look at the test flow itself. Maybe starting by always creating a test image when production release is created. It also looks now that in every project almost the same base Dockerfile is used with minor differences and a lot of different flavors. So maybe a single multistage image can be better used for this use case.
I at least think that there is a lot more room for optimizations but I think more input is needed to get the best solution.