Revert "[maven-release-plugin] prepare for next development iteration"

This reverts commit 1b0b8e205ebfdcc8e081e4e429dbcdb838ad9359.
Revert "[maven-release-plugin] prepare release pangool-top-level-0.60.3"

This reverts commit ec5154d8f8d136f58af14869c6541fad80a157ed.