chore: rm unused type (#6921)

crates/config/src/etherscan.rs

@@ -13,9 +13,6 @@ use std::{
     time::Duration,
 };
 
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct MaybeEtherscanApiKey(pub Option<String>);
-
 /// The user agent to use when querying the etherscan API.
 pub const ETHERSCAN_USER_AGENT: &str = concat!("foundry/", env!("CARGO_PKG_VERSION"));