message: nydus-image: add comments about allowing useless_conversion
diff: @@ -264,6 +264,9 @@ impl Bootstrap {
  }
  // dot & dotdot
  + // Type of libc::S_IFDIR is u16 on macos, so it need a conversion
  + // but compiler will report useless conversion on linux platform,
  + // so we add an allow annotation here.
  #[allow(clippy::useless_conversion)]
  {
  node.dirents
  