python: Remove redundant dest for argparse arguments.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

zerver/management/commands/generate_multiuse_invite_link.py

@@ -14,13 +14,11 @@ class Command(ZulipBaseCommand):
 
         parser.add_argument(
             '-s', '--streams',
-            dest='streams',
             type=str,
             help='A comma-separated list of stream names.')
 
         parser.add_argument(
             '--referred-by',
-            dest='referred_by',
             type=str,
             help='Email of referrer',
             required=True,