message: Correct JS stream purge subject
diff: @@ -581,7 +581,7 @@ impl Manager {
  "the stream name must not be empty",
  ));
  }
  - let subject = format!("STREAM.PURGE.{}", stream);
  + let subject = format!("$JS.API.STREAM.PURGE.{}", stream);
  self.request(&subject, b"")
  }
  