[MANTRUN-219] Bump xmlunit from 2.6.3 to 2.6.4

Bumps [xmlunit-core](https://github.com/xmlunit/xmlunit) from 2.6.3 to 2.6.4.
- [Release notes](https://github.com/xmlunit/xmlunit/releases)
- [Changelog](https://github.com/xmlunit/xmlunit/blob/master/RELEASE_NOTES.md)
- [Commits](xmlunit/xmlunit@v2.6.3...v2.6.4)

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

pom.xml

@@ -108,13 +108,13 @@ under the License.
     <dependency>
       <groupId>org.xmlunit</groupId>
       <artifactId>xmlunit-core</artifactId>
-      <version>2.6.3</version>
+      <version>2.6.4</version>
       <scope>test</scope>
     </dependency>
     <dependency>
       <groupId>org.xmlunit</groupId>
       <artifactId>xmlunit-matchers</artifactId>
-      <version>2.6.3</version>
+      <version>2.6.4</version>
       <scope>test</scope>
     </dependency>
   </dependencies>