fix: returning new gr.Slider fails to update existing slider

[andrewwhitecdw]

This PR addresses the following issue in examples/04_visualize_gradio.py: returning new gr.Slider fails to update existing slider.

Changes

• examples/04_visualize_gradio.py: returning new gr.Slider fails to update existing slider.

Details

Before:

    slider = gr.Slider(value=0, minimum=0, maximum=len(context.reader) - 1, step=1)
    return main + [slider]

After:

    slider_update = gr.update(value=0, minimum=0, maximum=len(context.reader) - 1, step=1)
    return main + [slider_update]