CI: Drop Ubuntu Oracular (24.10) boot test

E: Failed getting release file http://archive.ubuntu.com/ubuntu/dists/oracular/Release

Fixes #442

Author: solardiz

.github/workflows/mkosi-boot.yml

@@ -13,7 +13,6 @@ jobs:
                     - focal
                     - jammy
                     - noble
-                    - oracular
                     - plucky
                     - questing
         steps: