Fixed build problem

app.py

@@ -21,7 +21,7 @@ user_input = st.text_input('Ask me a question')
 if st.button("Submit"): 
     if user_input: 
         messages = [
-            {"role": "system", "content": f"Context: {context}"
+            {"role": "system", "content": f"Context: {context}"},
             {"role": "user","content": user_input}
         ]