Update app.py

app.py

@@ -68,7 +68,7 @@ Answer the user's questions only based on the PDF content above. If the answer c
         messages= [
             {"role": "system", "content": system_message},
         ]
-        for h_user , h_bot in history:
+        for h_user, h_bot in history:
             messages.append({"role": "user", "content": h_user})
             messages.append({"role": "assistant", "content": h_bot})