Make use_future take an impl FnMut + 'static, don't include router prelude when we don't need to

examples/simple_router.rs

@@ -1,7 +1,6 @@
 #![allow(non_snake_case)]
 
 use dioxus::prelude::*;
-use dioxus::router::prelude::*;
 
 #[derive(Routable, Clone, PartialEq)]
 enum Route {