Use backticks when referring to core::future::Ready in panic message

library/core/src/future/ready.rs

@@ -20,7 +20,7 @@ impl<T> Future for Ready<T> {
 
     #[inline]
     fn poll(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<T> {
-        Poll::Ready(self.0.take().expect("Ready polled after completion"))
+        Poll::Ready(self.0.take().expect("`Ready` polled after completion"))
     }
 }