spec: Require ldns-utils
    
    drill util helps to get information about DNSSEC for testing.
    
    Fixes: https://pagure.io/freeipa/issue/8094
    Signed-off-by: Stanislav Levin <slev@altlinux.org>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Christian Heimes <cheimes@redhat.com>