Remove serveo

It's been down for a long time.

README.md

@@ -81,7 +81,6 @@ easy tool to use, and is targeted at non-developers.
 * [gw.run](https://gw.run/) - Specifically focusing on securely exposing internal web apps to a group of people; not for publicly facing apps. Share access via email address then allow users to log in with common login providers like Google.
 * [SSHReach.me](https://sshreach.me/) - Paid SSH-based option. Uses a simple python script.
 * [KubeSail](https://kubesail.com/) - Company offering tunneling, dynamic DNS, and other services for self-hosting with Kubernetes.
-* [serveo](https://serveo.net) - Mentioned quite a bit the last couple years, but appears to be down currently. Simply uses SSH for tunneling.
 
 
 # Reference