Fix Clippy for Rust 1.90 beta (#7826)

Fix Clippy for recently released Rust 1.90 beta. There may be more changes required when Rust 1.89 stable is released in a few days, but possibly not 🤞

beacon_node/genesis/src/interop.rs

@@ -169,7 +169,7 @@ fn alternating_eth1_withdrawal_credentials_fn<'a>(
     pubkey: &'a PublicKey,
     spec: &'a ChainSpec,
 ) -> Hash256 {
-    if index % 2usize == 0usize {
+    if index.is_multiple_of(2) {
         bls_withdrawal_credentials(pubkey, spec)
     } else {
         eth1_withdrawal_credentials(pubkey, spec)