[Improvement] fix discourse loader to avoid rate limit (#953)

Co-authored-by: Deven Patel <deven298@yahoo.com>

embedchain/loaders/substack.py

@@ -1,6 +1,7 @@
-import time
 import hashlib
 import logging
+import time
+
 import requests
 
 from embedchain.helper.json_serializable import register_deserializable