message: fix value_of_i32
diff: @@ -331,7 +331,10 @@ pub trait ArgMatchesExt {
  let arg = match self._value_of(name) {
  None => None,
  Some(arg) => Some(arg.parse::<i32>().map_err(|_| {
  - clap::Error::value_validation_auto(format!("could not parse `{}` as a number", arg))
  + clap::Error::raw(
  + clap::ErrorKind::ValueValidation,
  + format!("Invalid value: could not parse `{}` as a number", arg),
  + )
  })?),
  };
  Ok(arg)
  