Update app.py

Change to Cortex Foundation subtensor

app.py

@@ -89,7 +89,7 @@ def run_with_retries(func, *args, **kwargs):
 
 def get_subtensor_and_metagraph() -> Tuple[bt.subtensor, bt.metagraph]:
     def _internal() -> Tuple[bt.subtensor, bt.metagraph]:
-        subtensor = bt.subtensor("finney")
+        subtensor = bt.subtensor("ws://finney.cortex.foundation:9944")
         metagraph = bt.metagraph(NETUID, lite=False)
         return subtensor, metagraph