message: nydus-image: use blake3 as default digester
  Blake3 is much faster than sha256, so use it as default.
diff: @@ -258,7 +258,7 @@ fn prepare_cmd_args(bti_string: &'static str) -> App {
  .long("digester")
  .help("Set algorithm to digest inodes and chunks:")
  .required(false)
  - .default_value("sha256")
  + .default_value("blake3")
  .value_parser(["blake3", "sha256"]),
  )
  .arg(
  