Update app.py

app.py

@@ -163,7 +163,7 @@ def chat_with_model(prompt, document_section, model_choice='gpt-3.5-turbo'):
     collected_chunks = []
     collected_messages = []
     key = os.getenv('OPENAI_API_KEY')
-    openai.api_key = key
+    client.api_key = key
     
     for chunk in client.chat.completions.create(
         model='gpt-3.5-turbo',