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

examples/clock.rs

@@ -7,7 +7,7 @@ fn main() {
 fn app() -> Element {
     let mut count = use_signal(|| 0);
 
-    use_future(|| async move {
+    use_future(move || async move {
         loop {
             tokio::time::sleep(std::time::Duration::from_millis(10)).await;
             count += 1;