use func_get_args to pass array_prepend call through to Arr::prepend to ensure correct handling of $key argument

Author: Jonathan Kraut

src/helpers.php

@@ -199,7 +199,7 @@ function array_pluck($array, $value, $key = null)
      */
     function array_prepend($array, $value, $key = null)
     {
-        return Arr::prepend($array, $value, $key);
+        return Arr::prepend(...func_get_args());
     }
 }