rpm: update dependency on qrexec

Policy engine (cli/daemon) accesses qubesd through a socket - must match
the protocol change.

rpm_spec/core-dom0.spec.in

@@ -74,7 +74,8 @@ Requires:       libvirt-python3
 
 Requires:       pciutils
 Requires:       qubes-core-dom0-linux >= 4.0.11
-Requires:       qubes-core-qrexec-dom0
+# policy (daemon) using changed qubesd socket protocol
+Requires:       qubes-core-qrexec-dom0 >= 4.1.8
 Requires:       qubes-db-dom0
 # TODO: R: qubes-gui-dom0 >= 2.1.11
 Conflicts:      qubes-gui-dom0 < 1.1.13