move to '3' approvals

plans/3.1.2/pmc-bug-approval.php

 <?php
 // votes required to be considered "approved"
-$nvotesRequired = 2;
+$nvotesRequired = 3;
 $targetMilestone="3.1.2";
 $targetMilestoneJPA="2.2.2";
 $debug = false;