fixed app.py - APP_ID retrieval (#3949)

samples/python/16.proactive-messages/app.py

@@ -63,7 +63,7 @@ async def on_error(context: TurnContext, error: Exception):
 # If the channel is the Emulator, and authentication is not in use, the AppId will be null.
 # We generate a random AppId for this case only. This is not required for production, since
 # the AppId will have a value.
-APP_ID = SETTINGS.app_id if SETTINGS.app_id else uuid.uuid4()
+APP_ID = CONFIG.APP_ID if CONFIG.APP_ID else uuid.uuid4()
 
 # Create the Bot
 BOT = ProactiveBot(CONVERSATION_REFERENCES)