MAPG-199 fix issues found by PHPStan

src/Database/Utils.php

@@ -1,7 +1,8 @@
 <?php namespace MapGuesser\Database;
 
 class Utils {
-    public static function backtick(string $name) {
+    public static function backtick(string $name): string
+    {
         return '`' . $name . '`';
     }
 }