www/py-django-reversion-compare: add missing dep

• added textproc/py-diff-match-patch as RUN_DEPENDS

While here, fix MAINTAINER as found by portlint

PR: 256809
Reported by: gettoknowmi <gettoknowmi@yahoo.com> (maintainer)

(cherry picked from commit cd6c4254801cb5cba1067f1189910c0b4ebfa5fb)