update column names

Signed-off-by: monica-sekoyan <msekoyan@nvidia.com>

app.py

@@ -408,7 +408,7 @@ with gr.Blocks(theme=nvidia_theme) as demo:
         download_btn_srt = gr.DownloadButton(label="Download SRT", visible=False)
 
     vis_timestamps_df = gr.DataFrame(
-        headers=["Start (s)", "End (s)", "Segment"],
+        headers=["Start", "End", "Segment"],
         datatype=["number", "number", "str"],
         wrap=True,
         label="Segments"