connection upgraded log space fix

Author: 0xb4lint

lib/smtp-connection.js

@@ -1461,7 +1461,7 @@ class SMTPConnection extends EventEmitter {
                     user: (this.session.user && this.session.user.username) || this.session.user,
                     cipher
                 },
-                'Connection upgraded to TLS using ',
+                'Connection upgraded to TLS using',
                 cipher || 'N/A'
             );
             this._server.onSecure(this._socket, this.session, err => {