feat: set 'auto' as default language value

- Change the default value of the language dropdown from an empty string to 'auto'
- This ensures a language is always selected by default, improving

projects/gradio_app/app.py

@@ -193,7 +193,7 @@ if __name__ == '__main__':
                 max_pages = gr.Slider(1, 20, 10, step=1, label='Max convert pages')
                 with gr.Row():
                     layout_mode = gr.Dropdown(['layoutlmv3', 'doclayout_yolo'], label='Layout model', value='doclayout_yolo')
-                    language = gr.Dropdown(all_lang, label='Language', value='')
+                    language = gr.Dropdown(all_lang, label='Language', value='auto')
                 with gr.Row():
                     formula_enable = gr.Checkbox(label='Enable formula recognition', value=True)
                     is_ocr = gr.Checkbox(label='Force enable OCR', value=False)