Udpate PyQt5 to 5.6.2
Update PyQt from 5.5.1 to 5.6.2 to match the Qt updates that have
already landed in the ports tree.
PR: 214355
Submitted by: Adriaan de Groot <groot@kde.org>
Reviewed by: rakuco, tcberner
Approved by: rakuco (mentor)
Exp-Run by: antoine
Differential Revision: https://reviews.freebsd.org/D8408