build(deps): bump xmlunit.version from 2.9.0 to 2.9.1

Bumps `xmlunit.version` from 2.9.0 to 2.9.1.

Updates `xmlunit-core` from 2.9.0 to 2.9.1
- [Release notes](https://github.com/xmlunit/xmlunit/releases)
- [Changelog](https://github.com/xmlunit/xmlunit/blob/main/RELEASE_NOTES.md)
- [Commits](xmlunit/xmlunit@v2.9.0...v2.9.1)

Updates `xmlunit-placeholders` from 2.9.0 to 2.9.1
- [Release notes](https://github.com/xmlunit/xmlunit/releases)
- [Changelog](https://github.com/xmlunit/xmlunit/blob/main/RELEASE_NOTES.md)
- [Commits](xmlunit/xmlunit@v2.9.0...v2.9.1)

---
updated-dependencies:
- dependency-name: org.xmlunit:xmlunit-core
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.xmlunit:xmlunit-placeholders
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

pom.xml

@@ -66,7 +66,7 @@
         <spring-web.version>5.3.24</spring-web.version>
         <mockito.version>4.11.0</mockito.version>
         <hamcrest.version>2.2</hamcrest.version>
-        <xmlunit.version>2.9.0</xmlunit.version>
+        <xmlunit.version>2.9.1</xmlunit.version>
         <skipTests>false</skipTests>
         <skipAssembly>false</skipAssembly>
         <deploy.plugin.repository.url>https://oss.sonatype.org/content/repositories/snapshots/</deploy.plugin.repository.url>