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/http_api/src/aggregate_attestation.rs

@@ -63,6 +63,6 @@ pub fn get_aggregate_attestation<T: BeaconChainTypes>(
     } else if endpoint_version == V1 {
         Ok(warp::reply::json(&GenericResponse::from(aggregate_attestation)).into_response())
     } else {
-        return Err(unsupported_version_rejection(endpoint_version));
+        Err(unsupported_version_rejection(endpoint_version))
     }
 }