[Tests] Fix incorrent twisted defer import

With the release Twisted 21.7.0 there was an import error running the
tests due to defer incorrectly imported via twisted.internet.tasks module.

deluge/tests/test_torrent.py

@@ -12,8 +12,8 @@ import time
 from base64 import b64encode
 
 import mock
-from twisted.internet import reactor
-from twisted.internet.task import defer, deferLater
+from twisted.internet import defer, reactor
+from twisted.internet.task import deferLater
 from twisted.trial import unittest
 
 import deluge.component as component