Add one more type

app.py

@@ -56,7 +56,7 @@ class SpotifyApi:
                     return final_mp3.as_posix()
 
 
-def process_inputs(prompt, audio, spotify_url):
+def process_inputs(prompt, audio, spotify_url) -> str:
     image = get_stable_diffusion_image(prompt)
     if spotify_url:
         spotify = SpotifyApi()