Remove un-necessary imports.

src/Http/Client/CookieCollection.php

@@ -13,8 +13,6 @@
  */
 namespace Cake\Http\Client;
 
-use Cake\Http\Client\Response;
-
 /**
  * Container class for cookies used in Http\Client.
  *

src/Http/Client/FormData.php

@@ -13,7 +13,6 @@
  */
 namespace Cake\Http\Client;
 
-use Cake\Http\Client\FormDataPart;
 use Countable;
 use finfo;