chore: update to bytes 1.0 git branch (#3301)

Updates the code base to track the `bytes` git branch. This is in
preparation for the 1.0 release.

Closes #3058

tokio-util/src/io/stream_reader.rs

@@ -131,7 +131,7 @@ where
         loop {
             if self.as_mut().has_chunk() {
                 // This unwrap is very sad, but it can't be avoided.
-                let buf = self.project().chunk.as_ref().unwrap().bytes();
+                let buf = self.project().chunk.as_ref().unwrap().chunk();
                 return Poll::Ready(Ok(buf));
             } else {
                 match self.as_mut().project().inner.poll_next(cx) {