remove require statements to non-existent classes.

tests/Zend/Feed/Pubsubhubbub/SubscriberHttpTest.php

@@ -23,7 +23,6 @@ require_once 'Zend/Feed/Pubsubhubbub/Subscriber.php';
 require_once 'Zend/Http/Client.php';
 require_once 'Zend/Http/Client/Adapter/Socket.php';
 require_once 'Zend/Uri/Http.php';
-require_once 'Zend/Feed/Pubsubhubbub/Entity/TopicSubscription.php';
 
 /**
  * Note that $this->_baseuri must point to a directory on a web server

tests/Zend/Feed/Pubsubhubbub/SubscriberTest.php

@@ -21,7 +21,6 @@
 
 require_once 'Zend/Feed/Pubsubhubbub/Subscriber.php';
 require_once 'Zend/Feed/Pubsubhubbub/Model/Subscription.php';
-require_once 'Zend/Feed/Pubsubhubbub/Entity/TopicSubscription.php';
 require_once 'Zend/Db/Table/Abstract.php';
 
 /**