Update app.py

app.py

@@ -1,7 +1,7 @@
 import gradio as gr
 import openai
 import os
-
+import tiktoken
 # Set your OpenAI API key
 openai.api_key = os.getenv('OPENAI_API_KEY')
 
@@ -23,7 +23,7 @@ def add_file(history, file):
     return history
 
 def num_tokens_from_messages(messages, model="gpt-3.5-turbo"):
-    encoding = openai.Encoding.from_model(model)
+    encoding = tiktoken.encoding_for_model(model)
     num_tokens = 0
     for message in messages:
         num_tokens += 4  # every message follows <im_start>{role/name}\n{content}<im_end>\n