Bump xmlunit.version from 2.8.0 to 2.8.1

Bumps `xmlunit.version` from 2.8.0 to 2.8.1.

Updates `xmlunit-core` from 2.8.0 to 2.8.1
- [Release notes](https://github.com/xmlunit/xmlunit/releases)
- [Changelog](https://github.com/xmlunit/xmlunit/blob/main/RELEASE_NOTES.md)
- [Commits](xmlunit/xmlunit@v2.8.0...v2.8.1)

Updates `xmlunit-matchers` from 2.8.0 to 2.8.1
- [Release notes](https://github.com/xmlunit/xmlunit/releases)
- [Changelog](https://github.com/xmlunit/xmlunit/blob/main/RELEASE_NOTES.md)
- [Commits](xmlunit/xmlunit@v2.8.0...v2.8.1)

Updates `xmlunit-legacy` from 2.8.0 to 2.8.1
- [Release notes](https://github.com/xmlunit/xmlunit/releases)
- [Changelog](https://github.com/xmlunit/xmlunit/blob/main/RELEASE_NOTES.md)
- [Commits](xmlunit/xmlunit@v2.8.0...v2.8.1)

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

Author: dependabot-preview[bot]

exist-parent/pom.xml

@@ -114,7 +114,7 @@
         <lucene.version>4.10.4</lucene.version>
         <milton.version>1.8.1.3</milton.version>
         <saxon.version>9.9.1-7</saxon.version>
-        <xmlunit.version>2.8.0</xmlunit.version>
+        <xmlunit.version>2.8.1</xmlunit.version>
 
         <!-- needed just for the license-maven-plugin in this module! -->
         <project.parent.relativePath>.</project.parent.relativePath>