Websocket dependency now depreciated

[oaklandcorp-jkaiser]

It appears that a dependency of this project has now been deprecated with maintenance moved to another repository. See pkg.go.dev for details. Here is a copy of the message:

deprecated: Use https://github.com/coder/websocket instead

A blog post seems to suggest maintenance is changing hands. If the new maintainer seems credible swapping to a maintained project seems like a good idea. It seems like Coder was the original author's employer at the time the library was created. They claim they have no breaking changes planned so hopefully that means a fairly painless transition.