contrib: download-frozen-image-v2.sh requires jq

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

contrib/download-frozen-image-v2.sh

@@ -11,6 +11,10 @@ if ! command -v curl &> /dev/null; then
 	echo >&2 'error: "curl" not found!'
 	exit 1
 fi
+if ! command -v jq &> /dev/null; then
+	echo >&2 'error: "jq" not found!'
+	exit 1
+fi
 
 usage() {
 	echo "usage: $0 dir image[:tag][@digest] ..."