build(deps-dev): bump xmlunit-core from 2.8.3 to 2.8.4

Bumps [xmlunit-core](https://github.com/xmlunit/xmlunit) from 2.8.3 to 2.8.4.
- [Release notes](https://github.com/xmlunit/xmlunit/releases)
- [Changelog](https://github.com/xmlunit/xmlunit/blob/main/RELEASE_NOTES.md)
- [Commits](xmlunit/xmlunit@v2.8.3...v2.8.4)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pom.xml

@@ -128,7 +128,7 @@
     <dependency>
       <groupId>org.xmlunit</groupId>
       <artifactId>xmlunit-core</artifactId>
-      <version>2.8.3</version>
+      <version>2.8.4</version>
       <scope>test</scope>
     </dependency>