Fix: AttributeError Dropdown has no attribute submit -> change

- gr.Dropdown does not have .submit() method, only .change()
- Changed model_name_gui.submit() to model_name.change() at line 2250
- Matches original code behavior

app.py

@@ -2247,7 +2247,7 @@ with gr.Blocks(elem_id="main", fill_width=True, fill_height=False) as app:
 
                     load_model_gui = gr.HTML(elem_id="load_model", elem_classes="contain")
 
-                    load_model_gui_event = model_name_gui.submit(
+                    load_model_gui_event = model_name_gui.change(
                         _load_model,
                         inputs=[model_name_gui, vae_model_gui, task_gui, controlnet_model_gui],
                         outputs=[load_model_gui, result_images, actual_task_info],