Require release date in the past

A release should be announced only after it has been released. We assume that the release has been released on its due date, which is stored in the app stream data, initially as a plan to release. We assume that versions with due date in future have not been released yet, so announcing the release as a fact would be inappropriate. While it is possible that a release has already happened when the script is running, much less harm arises from a little delay than from a premature announcement.