Add an xml comment wrt Mockito 4 vs 5

Author: cowtowncoder

pom.xml

@@ -54,6 +54,10 @@
     <version.android.sdk.signature>0.12.0</version.android.sdk.signature>
 
     <version.bytebuddy>1.15.10</version.bytebuddy>
+
+    <!-- 25-Sep-2025, tatu: Last 4.x Mockito: 5.x requires JDK 11 so
+          cannot upgrade further
+      -->
     <version.mockito>4.11.0</version.mockito>
 
     <!-- 07-Apr-2025, tatu: For some reason, release fails due to missing