Publish installer-v1.28.0: move both git-sync refs to the new tag

Pushing publishes nothing here - /scripts/ follows the installer TAG, and both the
sidecar and the init container carry the ref. Verified against the live URL after
the sync, because the runbook still says otherwise (R-309, still open).

manifests/webpage.yaml

@@ -324,7 +324,7 @@ spec:
           image: registry.k8s.io/git-sync/git-sync:v4.4.0
           args:
             - --repo=https://gitea.dooplex.hu/admin/felhom.eu.git
-            - --ref=installer-v1.27.0
+            - --ref=installer-v1.28.0
             - --root=/git-scripts
             - --link=current
             - --period=30s
@@ -369,7 +369,7 @@ spec:
           image: registry.k8s.io/git-sync/git-sync:v4.4.0
           args:
             - --repo=https://gitea.dooplex.hu/admin/felhom.eu.git
-            - --ref=installer-v1.27.0
+            - --ref=installer-v1.28.0
             - --root=/git-scripts
             - --link=current
             - --one-time