Use versioned antora ui

antora-playbook.yml

@@ -33,7 +33,7 @@ urls:
   redirect_facility: httpd
 ui:
   bundle:
-    url: https://github.com/spring-io/antora-ui-spring/releases/download/latest/ui-bundle.zip
+    url: https://github.com/spring-io/antora-ui-spring/releases/download/v0.3.0/ui-bundle.zip
     snapshot: true
 runtime:
   log:

lib/antora/templates/per-branch-antora-playbook.yml

@@ -34,5 +34,5 @@ runtime:
     failure_level: warn
 ui:
   bundle:
-    url: https://github.com/spring-io/antora-ui-spring/releases/download/latest/ui-bundle.zip
+    url: https://github.com/spring-io/antora-ui-spring/releases/download/v0.3.0/ui-bundle.zip
     snapshot: true