Add automatic version arguments to the CI pipeline.

[tmeire]

TODO: Define a versioning strategy and pass in the automated version to the docker build process.

[tmeire]

Development should follow a trunk-based development flow with semantic versioning. New versions need to be tagged manually. Preferably, each minor release has its own release branch release-X.Y where (pre-)releases are tagged with a tag like vX.Y.Z(-rc.W). Tags will trigger the build workflow which will push the docker image to ghcr on success.

Fixed in #14