Trigger a rebuild of docker/dashboard2 [bookworm]

This MR adds a trigger to rebuild docker/dashboard2 when this container is rebuilt.

.gitlab/ci/trigger.yml

@@ -16,6 +16,11 @@ rebuild:builder:
   trigger:
     project: docker/builder
 
+rebuild:dashboard2:
+  extends: [.rebuild]
+  trigger:
+    project: docker/dashboard2
+
 rebuild:lalsuite-dev:
   extends: [.rebuild]
   trigger: