Make errors in Routes Infallible.

[BratSinot]

Greetings!

Motivation

So, why there boxed error instead of Infallible? There are no errors in these part, but because there boxed error it makes problem to use like this: P.S. MultiplexService taken from there: https://github.com/tokio-rs/axum/blob/main/examples/rest-grpc-multiplex/src/multiplex_service.rs

    let grpc = tonic::transport::Server::builder()
        .add_service(WorkspaceServiceServer::new(workspace))
        .add_service(health_service)
        .into_service();

    let rest = axum::Router::new().route("/", get(|| async { "Hello".to_owned() }));

    let service = MultiplexService::new(management, grpc);

    axum::Server::bind(&address)
        .serve(tower::make::Shared::new(service))
        .await
        .unwrap();

[LucioFranco]

Hmm this seems fine, only issue is that tonic just released a breaking change, so this will have to wait a bit. In addition, eventually the whole transport module will go away so I suspect it we will fix it via this or just remove all this code (still figuring out those timelines).