minor: Fix imports in test_xkcd.py.
We no longer need the `future` imports and we can
use `StubBotTestCase` now.
MODIFY
zulip_bots/zulip_bots/bots/xkcd/test_xkcd.py
zulip_bots/zulip_bots/bots/xkcd/test_xkcd.py
#!/usr/bin/env python
-from __future__ import absolute_import
-from __future__ import print_function
-
import mock
from mock import MagicMock, patch
-from zulip_bots.test_lib import BotTestCase
+from zulip_bots.test_lib import StubBotTestCase
-class TestXkcdBot(BotTestCase):
+class TestXkcdBot(StubBotTestCase):
bot_name = "xkcd"
def test_latest_command(self):

minor: Fix imports in test_xkcd.py.

We no longer need the `future` imports and we can
use `StubBotTestCase` now.