fix: Remove more as conversions in protocol::messages

[pierwill]

Part of #101.

[pierwill]

Should this be .map_err(|e| ReadVersionedError::ReadError(ReadError::Overflow(e)))??

[crepererum]

I think thiserror and ? take care of that:

rskafka/src/protocol/messages/mod.rs

Lines 40 to 44 in 2c13f4b

	#[derive(Error, Debug)]
	pub enum ReadVersionedError {
	#[error("Read error: {0}")]
	ReadError(#[from] ReadError),
	}

See the #[from] macro. Also note that ? doesn't mean "return this error" but "return this error, rustc might apply a From/Into conversion. So

let x = f()?;

is more or less

let x = match f() {
    Ok(x) => x,
    Err(e) => {
        return e.into();
    }
};