yoda bot: Just import the requests module.

This removes the unconventional check for the
existence of the requests module in the yoda
bot to bring it in line with other bots.

zulip_bots/zulip_bots/bots/yoda/yoda.py

@@ -2,11 +2,7 @@
 import logging
 import ssl
 import sys
-try:
+import requests
-    import requests
-except ImportError as e:
-    logging.error("Dependency missing!!\n{}".format(e))
-    sys.exit(0)
 
 from typing import Any, Dict