Refactor predict function to retrieve user message using get_user_message method

app.py

@@ -231,7 +231,7 @@ def predict(state,
 
         history = state.get_history()
         logger.info(f"====  History ====\n{history}")
-        message = history[-1][0] if len(history) > 0 else ""
+        _, message = state.get_user_message(source=state.USER, position='last')
 
         logger.info(f"==== Lenght Pixel values ====\n{len(pixel_values)}")
         
@@ -294,6 +294,7 @@ def ai_bot(
         # Stream output
         logger.info(f"==== Image paths ====\n{all_image_paths}")
 
+
         response, _ = predict(state,
                             all_image_paths[0] if len(all_image_paths) > 0 else None,
                             max_input_tiles,