system-config-printer: 1.5.11 -> 1.5.12

Source for the change of upstream url:
* zdohnal/system-config-printer is a fork of
OpenPrinting/system-config-printer
* This is what fedora did:
https://apps.fedoraproject.org/packages/system-config-printer/sources/spec/
(see changelog for  1.5.11-17)