NXCM-5424: Added p-u as direct dependency of the plugin

As SecDispatcher mojo commons uses to decrypt passwords
need it, and older versions of p-u lacks XmlStreamReader class.

This change will "pintpoint" p-u 3.0,8 (as defined in parent) as (explicit)
dependency of this plugin, and should fix NXCM-5424 where Maven "gave"
p-u 1.1 instead (as it was implicit dependency).


Issue
https://issues.sonatype.org/browse/NXCM-5424