sysutils/duply: update to 2.2.2 and fix broken MASTER_SITES

The previous MASTER_SITES entry was actually a redirect to
SourceForge, however, it appears it was only ever capable of
retrieving the latest version of duply. This meant that when a new
upstream version of duply was released, the port would break as
duply.net always redirected to the latest version, no matter which
version you were actually requesting.

This is resolved by pointing MASTER_SITES to the real SourceForge
location for the releases.

Changelog: http://duply.net/Changelog-TODO

PR: 241784
Reported by: David O'Rourke <dor.bsd@xm0.uk>
Approved by: michael@ranner.eu (maintainer)