fix: dev: [vps] small typo in error message of ``vps backup``

bin/vps

@@ -958,12 +958,12 @@ compose:get_cron_docker_cmd() {
     }
     if docker exec "$container" test -e /etc/cron.d/rsync-backup; then
         if ! cron_line=$(docker exec "${project_name}"_cron_1 cat /etc/cron.d/rsync-backup | grep "\* \* \*"); then
-            err "Can't find cron_line in cron container."
+            err "Can't find cron line in legacy cron container."
             return 1
         fi
     elif docker exec "$container" test -e /etc/crontabs/root; then
         if ! cron_line=$(docker exec "$container" cat /etc/crontabs/root | grep " launch-rsync-backup " | grep "\* \* \*"); then
-            err "Can't find cron_line in cron container."
+            err "Can't find cron line in cron container."
             return 1
         fi
     else