Update src/lib.rs

Fix a typo in the comment.

Co-authored-by: Sebastian Dröge <sebastian@centricular.com>

src/lib.rs

@@ -273,7 +273,7 @@ where
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
         trace!("{}:{} Stream.poll_next", file!(), line!());
 
-        // The connection has been closed or the critical error has occurred.
+        // The connection has been closed or a critical error has occurred.
         // We have already returned the error to the user, the `Stream` is unusable,
         // so we assume that the stream has been "fused".
         if self.ended {