Update Antora Spring UI to v0.4.25

Closes gh-35876

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

framework-docs/antora-playbook.yml

@@ -36,4 +36,4 @@ runtime:
     failure_level: warn
 ui:
   bundle:
-    url: https://github.com/spring-io/antora-ui-spring/releases/download/v0.4.22/ui-bundle.zip
+    url: https://github.com/spring-io/antora-ui-spring/releases/download/v0.4.25/ui-bundle.zip