rpm: drop uneeded dependencies:

gnome-packagekit: no longer needed, especially not in this package;
qubes-dom0-update tool is in core-dom0-admin-linux, but preffer a `dnf
update` in a terminal emulator

bsdtar: was used by 3.x DispVM implementation, now isn't used anywhere

rpm_spec/core-dom0.spec.in

@@ -85,9 +85,7 @@ Requires:       xen-hvm-stubdom-linux
 Requires:       libvirt-daemon-xen >= 3.3.0-7
 %endif
 Requires:       createrepo
-Requires:       gnome-packagekit
 Requires:       cronie
-Requires:       bsdtar
 Requires:       scrypt
 # for qubes-hcl-report
 Requires:       dmidecode