configure secret key for hf token in app.py

app.py

@@ -1,7 +1,10 @@
 import gradio as gr
+import os
+
+hf_key = os.getenv("HF_TOKEN")
 
 demo = gr.load("huggingface/facebook/fastspeech2-en-ljspeech",
-        token = HF_TOKEN,
+        token = hf_key,
         description="TTS using FastSpeech2",
         title="Text to Speech (TTS)",
         examples=[["The quick brown fox jumps over the lazy dog."]]