time: implement FusedStream for IntervalStream (#7854)

tokio-stream/src/wrappers/interval.rs

@@ -1,4 +1,5 @@
 use crate::Stream;
+use futures_core::stream::FusedStream;
 use std::pin::Pin;
 use std::task::{Context, Poll};
 use tokio::time::{Instant, Interval};
@@ -57,6 +58,12 @@ impl Stream for IntervalStream {
     }
 }
 
+impl FusedStream for IntervalStream {
+    fn is_terminated(&self) -> bool {
+        false
+    }
+}
+
 impl AsRef<Interval> for IntervalStream {
     fn as_ref(&self) -> &Interval {
         &self.inner