[CoreOS] Fedora CoreOS rebasing to Fedora Linux 39

Fedora Linux 39 was released today [1]. The Fedora CoreOS `testing` stream has been rebased and is currently rolling out. In two weeks, it will be promoted to the `stable` stream. For more information about Fedora 39, see the Fedora Project's list of official Changes [2] and the Fedora CoreOS analysis of each Change [3]. As mentioned in a previous announcement, there are a few changes related to modularity, AWS AMIs, and `moby-engine` that require special attention. For more information, see [4]. Thank you to everyone helping find issues by running the `next` and `testing` streams! Dusty Mabe, for the Fedora CoreOS team [1]: https://fedoramagazine.org/announcing-fedora-linux-39/ [2]: https://fedoraproject.org/wiki/Releases/39/ChangeSet [3]: https://github.com/coreos/fedora-coreos-tracker/issues/1491 [4]: https://discussion.fedoraproject.org/t/90321