WebSocket Dial Handshake 403 When Connecting to Server Written Using x/net/websocket

We have a simplistic example websocket server written using this boilerplate in the labstack echo cookbook: https://echo.labstack.com/docs/cookbook/websocket#server

It's currently using `x/net/websocket`. On the client side that connects to this example server, I tried to swap out our `x/net/websocket` implementation for `nhooyr/websocket`, but when `websocket.Dial` is called, the handshake fails with this 403 error. I'm not sure why this is, as the default CORS for `echo` is to allow everything and if I swap back to the dialer in `x/net/websocket`, it works fine. Just in case, I've tried to provide a custom HTTP client with a custom transport that sets `InsecureSkipVerify: true` via the `DialOptions`, but this also did not work.

Start at websocket.Dial and reproduce the 403 handshake against the Echo cookbook server, using the linked server example as the test case. Compare the failing client request with the working x/net/websocket connection and the reported custom DialOptions transport; done means the client completes the handshake with that server.

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