MAPG-235 fix user deletion bug

database/migrations/structure/20210510_2000_challenge.sql

@@ -48,6 +48,6 @@ CREATE TABLE `guesses` (
   PRIMARY KEY (`id`),
   KEY `user_id` (`user_id`),
   KEY `place_in_challenge_id` (`place_in_challenge_id`),
-  CONSTRAINT `guesses_user_id` FOREIGN KEY (`user_id`) REFERENCES `places` (`id`),
+  CONSTRAINT `guesses_user_id` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`),
   CONSTRAINT `guesses_place_in_challenge_id` FOREIGN KEY (`place_in_challenge_id`) REFERENCES `place_in_challenge` (`id`)
 ) ENGINE = InnoDB DEFAULT CHARSET = utf8mb4;