Update to antora-ui-spring v0.4.25

Author: rwinch

antora-playbook.yml

@@ -34,8 +34,7 @@ urls:
   redirect_facility: httpd
 ui:
   bundle:
-    url: https://github.com/spring-io/antora-ui-spring/releases/download/v0.4.18/ui-bundle.zip
-    snapshot: true
+    url: https://github.com/spring-io/antora-ui-spring/releases/download/v0.4.25/ui-bundle.zip
 runtime:
   log:
     level: info