www/rt50: add dependency on textproc/p5-Pod-Parse

Add dependency on textproc/p5-Pod-Parse:
RT::Shredder::POD uses Pod::Select, which is provided by
textproc/p5-Pod-Parser

While here, fix rt-test-dependencies by providing the correct path

PR: 250197
Reported by: David Siebörger
MFH: 2020Q4 (blanket: runtime fix)