IO-747 Enable moditect plugin when building with Java 9+
IO-747 Enable moditect plugin when building with Java 9+

Enforce that Java 9+ is being used for releases

Suggested-by: Jochen Wiedmann at https://github.com/apache/commons-io/pull/268/files#r707160987

apache/commons-io,apache/commons-io,apache/commons-io