[tracker/wip/carlosg/backports-3.3] ci: Do not test build website on non-main branch

[Carlos Garnacho <carlosg src gnome org>]

commit 53069369187255d22a7edd4fc917c9c2b25edd52
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Jul 5 16:14:47 2022 +0200

    ci: Do not test build website on non-main branch

 .gitlab-ci.yml | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index ff06146bd..25cdd5cec 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -387,6 +387,8 @@ test-website:
       - website
   needs:
     - build-fedora-container@x86_64
+  only:
+    - master
 
 coverage:
   extends: