fix: change smtp-user to smtp-username

cubicweb/cwconfig.py

@@ -1248,7 +1248,7 @@ the repository',
         if connection to the smtp server failed, else True.
         """
         server, port = self['smtp-host'], self['smtp-port']
-        smtp_user, smtp_password = self['smtp-user'], self['smtp-password']
+        smtp_user, smtp_password = self['smtp-username'], self['smtp-password']
         if fromaddr is None:
             fromaddr = '%s <%s>' % (self['sender-name'], self['sender-addr'])
         SMTP_LOCK.acquire()