webkit: Skip the repos

This will help testing the newer WebKitGTK version without affecting the
current repos.

jobs.yml

@@ -250,6 +250,7 @@ webkit:
   deb_build_options: ['nocheck', 'parallel=4']
   deb_build_profiles: ['nocheck']
   sloppy: true
+  repo: skip
 wlroots:
   url: https://source.puri.sm/Librem5/wlroots.git
   dists: ['buster']