backend.rs defines its own BoxFuture type alias (Pin<Box<dyn Future + Send>>) using std::future::Future + futures_core, so the futures crate is unused. Removes the dead dependency.
backend.rs defines its own BoxFuture type alias (Pin<Box<dyn Future + Send>>) using std::future::Future + futures_core, so the futures crate is unused. Removes the dead dependency.