rpm: update required qubes-core-dom0 version

It is needed for qubesos/qubes-issues#892 implementation.

rpm_spec/qmgr.spec

@@ -11,7 +11,7 @@ Group:		Qubes
 Vendor:		Invisible Things Lab
 License:	GPL
 URL:		http://fixme
-Requires:	python, PyQt4, qubes-core-dom0-linux >= 2.0.22, qubes-core-dom0 >= 2.1.57
+Requires:	python, PyQt4, qubes-core-dom0-linux >= 2.0.22, qubes-core-dom0 >= 3.0.18
 Requires:	pmount, cryptsetup, wmctrl
 Requires:	dbus
 Requires:	qubes-artwork