Merge pull request #10506 from Icinga/Fedora42

GHA: add Fedora 42

Author: julianbrost

.github/workflows/linux.yml

@@ -36,6 +36,7 @@ jobs:
           - fedora:39
           - fedora:40
           - fedora:41
+          - fedora:42
 
           - opensuse/leap:15.5
           - opensuse/leap:15.6