Use at least xorriso 1.5.6

Set the OBS specfile to use at least version 1.5.6.

Signed-off-by: Fredrik Lönnegren <fredrik.lonnegren@suse.com>

.obs/specfile/elemental-toolkit.spec

@@ -34,7 +34,7 @@ Requires:       parted
 Requires:       rsync
 Requires:       udev
 Requires:       xfsprogs
-Requires:       xorriso
+Requires:       xorriso >= 1.5.6
 Requires:       mtools
 Requires:       util-linux
 Requires:       gptfdisk