chore(backend): apply clippy suggestion

[MichaIng]

https://rust-lang.github.io/rust-clippy/master/index.html#/get_first
https://rust-lang.github.io/rust-clippy/master/index.html#/no_effect_underscore_binding

These seem to break https://nightly.link/.

I am not 100% sure whether the token argument in socket_handler is really unused? As far as I understand, it is, respectively it is overwritten with String::new() and probably some remain from the token handling change, and the token is now obtained within socket_handler?

EDIT: Okay, at last the websocket connections pass a token to this function:

            if let Some(token) = token {
                response = websocket(
                    req,
                    crate::socket_handlers::term_handler,
                    span,
                    token.to_string(),
                )?;

So since I am not 100% sure whether I understand the code correctly, Instead the warning is not ignored.

[MichaIng]

@ravenclaw900 I injected this commit here: #758
Still not sure about the unused _token, but it bringts us forward to have CI green, and the other change is trivial.