Upgrade to xmlunit 1.6

Author: gaul

project/pom.xml

@@ -243,7 +243,7 @@
 
     <!-- Test dependency versions -->
     <testng.version>7.5.1</testng.version>
-    <xmlunit.version>1.3</xmlunit.version>
+    <xmlunit.version>1.6</xmlunit.version>
     <assertj-core.version>3.23.1</assertj-core.version>
     <assertj-guava.version>1.3.0</assertj-guava.version>