Update app.py

app.py

@@ -83,7 +83,7 @@ dict = {
 
 def text_to_speech(text, language_code):
     # Replace with your own subscription key and region identifier from Azure portal
-    subscription_key = os.getenv('subscription_key')
+    subscription_key = os.environ['subscription_key']
     region = "eastus"
 
     # Creates an instance of a speech config with specified subscription key and service region.