switch to distil medium, cleanup code

app.py

@@ -2,11 +2,10 @@ import gradio as gr
 import spaces
 import torch
 import io
-import os.path
-from huggingface_hub import hf_hub_download
 import whisper
+from huggingface_hub import hf_hub_download
 
-model_path = hf_hub_download(repo_id="distil-whisper/distil-large-v3-openai", filename="model.bin")
+model_path = hf_hub_download(repo_id="distil-whisper/distil-medium.en", filename="original-model.bin")
 
 writer = whisper.utils.get_writer("srt", "/dev/null")