Fix clippy warnings (#1385)

## Issue Addressed

NA

## Proposed Changes

Fixes most clippy warnings and ignores the rest of them, see issue #1388.

beacon_node/src/lib.rs

@@ -126,7 +126,7 @@ impl<E: EthSpec> ProductionBeaconNode<E> {
 
         let builder = builder
             .build_beacon_chain()?
-            .network(&mut client_config.network)?
+            .network(&client_config.network)?
             .notifier()?;
 
         let builder = if client_config.rest_api.enabled {