Add Zend_Feed to the list of obsolete classes

Author: Ben Batschelet

dev/tests/static/testsuite/Magento/Test/Legacy/_files/obsolete_classes.php

@@ -4212,4 +4212,5 @@
     ['Magento\Framework\Acl\CacheInterface'],
     ['Magento\Framework\Acl\Test\Unit\CacheTest'],
     ['Magento\Eav\Model\Entity\Attribute\Backend\Serialized'],
+    ['Zend_Feed', 'Zend\Feed'],
 ];