build: move netpbm-progs (screenshot scale/convert) to striker dependencies

anvil.spec.in

@@ -135,6 +135,7 @@ Requires:       firefox
 Requires:       gcc
 Requires:       gdm
 Requires:       gnome-terminal
+Requires:       netpbm-progs
 Requires:       nmap
 Requires:       nodejs
 Requires:       openssh-askpass
@@ -164,7 +165,6 @@ Requires:       libvirt-daemon
 Requires:       libvirt-daemon-driver-qemu 
 Requires:       libvirt-daemon-kvm 
 Requires:       libvirt-docs 
-Requires:       netpbm-progs
 Requires:       pacemaker 
 Requires:       pcs 
 Requires:       python3-websockify
@@ -196,7 +196,6 @@ Requires:       libvirt-daemon
 Requires:       libvirt-daemon-driver-qemu 
 Requires:       libvirt-daemon-kvm 
 Requires:       libvirt-docs 
-Requires:       netpbm-progs
 Requires:       python3-websockify
 Requires:       qemu-kvm 
 Requires:       qemu-kvm-core