fixup! fixup! Fix AddressList toString method to quote semicolon

Author: glensc

test/Storage/MessageTest.php

@@ -10,6 +10,7 @@
 
 use Exception as GeneralException;
 use Laminas\Mail\Exception as MailException;
+use Laminas\Mail\Headers;
 use Laminas\Mail\Storage;
 use Laminas\Mail\Storage\Exception;
 use Laminas\Mail\Storage\Message;