fix: missing brackets

Author: TorstenDittmann

src/Database/Validator/Queries.php

@@ -43,7 +43,7 @@ public function __construct($validator, $indexes, $strict = true)
 
         $this->indexes[] = [
             'type' => Database::INDEX_UNIQUE,
-            'attributes' => '$id'
+            'attributes' => ['$id']
         ];
 
         foreach ($indexes as $index) {