packit: Enable fedora-42 test

This has worked for some time, and is enabled in all our other projects,
we just forgot about it here.

Author: martinpitt

packit.yaml

@@ -30,8 +30,7 @@ jobs:
     trigger: pull_request
     targets:
       - fedora-41
-      # https://pagure.io/fedora-infrastructure/issue/12389
-      # - fedora-42
+      - fedora-42
       - fedora-latest-stable-aarch64
       - fedora-rawhide
       - centos-stream-9-x86_64