Due to maintenance at 17.06.2025 from 8:00 to 09:00, git.rwth-aachen.de & git-ce.rwth-aachen.de will be temporarily unavailable. In maintenance, GitLab is updated to version 18. Information about changes can be found at: https://about.gitlab.com/blog/2025/04/18/a-guide-to-the-breaking-changes-in-gitlab-18-0/#breaking-changes
This MR adds the new stages package and upload to the CI pipeline. The upload job is only performed for Version-Tags (vX.X.X), which are protected in GitLab to be only created by Maintainers.
Additionally, this MR fixes the setup.py to exclude the tests from the distribution package.