ci: Add empty needs: to pages job

So it doesn't need to wait for jobs in earlier stages.

Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6209>
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 3f6e1cc..4ad29d7 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -84,6 +84,7 @@
   artifacts:
     paths:
     - public
+  needs: []
   rules:
     - *ignore_scheduled_pipelines
     - if: *is-main-master