Update CHANGES.md

Author: tomaswolf

CHANGES.md

@@ -28,6 +28,7 @@
 
 ## Bug Fixes
 
+* [GH-516](https://github.com/apache/mina-sshd/issues/516) SFTP: allow file system URIs without password
 * [GH-650](https://github.com/apache/mina-sshd/issues/650) Use the correct key from a user certificate in server-side pubkey auth
 * [GH-663](https://github.com/apache/mina-sshd/issues/663) Fix racy `IoSession` creation
 * [GH-664](https://github.com/apache/mina-sshd/issues/664) Skip MAC negotiation if an AEAD cipher was negotiated