www/serendipity: Update from 2.0.4 to 2.0.5

Changelog: https://blog.s9y.org/archives/271-Serendipity-2.0.5-and-2.1-beta3-released.html

PR: 214948
Submitted by: Jochen Neumeister <joneum@bsdproject.de>
Approved by: mentors (implicit)
MFH: 2016Q4