Update Java version requirement to Java 17

The library requires Java 17+ as it uses Java records and the pom.xml
specifies <release>17</release>.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: oschwald

README.md

@@ -547,7 +547,7 @@ to the client API, please
 
 ## Requirements  ##
 
-MaxMind has tested this API with Java 11 and above.
+MaxMind has tested this API with Java 17 and above.
 
 ## Contributing ##