Support #[serde(untagged)]

[wagmi-lotech]

It would be great if we could define catch-all variant that would retain underlying data on deserialization. While this library does support #[serde(other)] already for a catch-all variant, this discards the data. It would be great if we could instead use #[serde(untagged)] - obviously just over a newtype-style variant with a single value that matches repr type:

#[derive(Deserialize_repr)]
#[repr(u8)]
enum Code {
    SomethingWentWrong = 5,
    SomeOtherError = 6,
    #[serde(untagged)]
    Other(u8),
}