Update Multishipping.php

Author: liam-wiltshire

app/code/Magento/GiftMessage/Model/Type/Plugin/Multishipping.php

@@ -32,7 +32,7 @@ public function __construct(
     /**
      * @param \Magento\Multishipping\Model\Checkout\Type\Multishipping $subject
      * @param array|null $methods
-     * @return $this
+     * @return void
      * @SuppressWarnings(PHPMD.UnusedFormalParameter)
      */
     public function beforeSetShippingMethods(