Bump com.thoughtworks.xstream:xstream from 1.4.20 to 1.4.21 (#1086)

Bumps [com.thoughtworks.xstream:xstream](https://github.com/x-stream/xstream) from 1.4.20 to 1.4.21.
- [Release notes](https://github.com/x-stream/xstream/releases)
- [Commits](https://github.com/x-stream/xstream/commits)

---
updated-dependencies:
- dependency-name: com.thoughtworks.xstream:xstream
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

pom.xml

@@ -287,7 +287,7 @@
 		<guava.version>33.3.1-jre</guava.version>
 		<wicket-webjars.version>4.0.5</wicket-webjars.version>
 		<jquery-selectors.version>4.0.6</jquery-selectors.version>
-		<xstream.version>1.4.20</xstream.version>
+		<xstream.version>1.4.21</xstream.version>
 		<hamcrest.version>3.0</hamcrest.version>
 		<jakarta.servlet-api.version>5.0.0</jakarta.servlet-api.version>
 		<junit.version>5.11.3</junit.version>