balanceOf calls fail in quickstart example

[quazzuk]

When running the quickstart example I see the following output:

Failed to get token balance: server returned an error response: error code -32602: missing value for required argument 1
Failed to get WETH balance: server returned an error response: error code -32602: missing value for required argument 1

Looks like this is due to the BlockId is not being set and defaulting to None resulting in it being absent from the eth_call

I fixed locally with the following:

let result = provider
        .call(&TransactionRequest {
            to: Some(TxKind::Call(token_address)),
            input: data.into(),
            ..Default::default()
        })
        .block(BlockId::latest())
        .await?;

I can push a PR, if you'd prefer?

Cheers