Update the links for the groupme protocol to the active repository

Testing Done:
Ran the devserver and verified everything looked okay.

Reviewed at
title: 3.0.0
date: 2019-09-04T02:46:13.000Z
anchor: 3.0.0
replaces: []
lastmod: 2019-09-04T03:42:40.000Z
Pidgin 3.0.0 is the in-development next major version of Pidgin. Its build
instructions are quite different than Pidgin 2.x.y and have not yet been
full documented.