enhance juniper::GraphQLEnum

[himself65]

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I want to display the integer on enum, like

#[derive(juniper::GraphQLEnum)]
pub enum Gender {
    Man = 0,
    Woman = 1,
}

and

field something(&executor, name: String) -> FieldResult<Something> {
  Ok(Something{
      gender: Gender::Man
  )
}

when I call it and it will display 0 on gender