app_queue.c: Fix json ref leak

Declining the queue_member_status_type stasis message in stasis.conf
causes these messages to leak json objects.

* Add missing ast_json_unref() if the type is NULL in
queue_publish_member_blob().

ASTERISK-28084

Change-Id: I691ecf49bd1f7d9c29182e1eee8c4bb7103be9fc

apps/app_queue.c

@@ -2255,6 +2255,7 @@ static void queue_publish_member_blob(struct stasis_message_type *type, struct a
 	RAII_VAR(struct stasis_message *, msg, NULL, ao2_cleanup);
 
 	if (!blob || !type) {
+		ast_json_unref(blob);
 		return;
 	}