"Update Colab public URL".

url.json

@@ -1 +1 @@
-{"url": "NgrokTunnel: \"https://51b7-34-75-74-176.ngrok-free.app\" -> \"http://localhost:5000\""}
+{"url": "NgrokTunnel: \"https://jrcw4bqqgbn-496ff2e9c6d22116-5000-colab.googleusercontent.com/\" -> \"http://localhost:5000\""}