[Bugfix] Add sleep when Discord rate limit

cron.py

@@ -36,7 +36,7 @@ def _send(maintainer, message):
     response = requests.post(discord, json=message_json)
     if response.status_code in [200, 204]:
         print("Webhook executed")
-        sleep(1)
+        time.sleep(1)
     else:
         print("status code {}: {}".format(response.status_code, response.content.decode("utf-8")))
         time.sleep(10)