Update discv5 (#3171)

## Issue Addressed

Updates discv5

Pending on
- [x] #3547 
- [x] Alex upgrades his deps

## Proposed Changes

updates discv5 and the enr crate. The only relevant change would be some clear indications of ipv4 usage in lighthouse

## Additional Info

Functionally, this should be equivalent to the prev version.
As draft pending a discv5 release

beacon_node/lighthouse_network/src/peer_manager/network_behaviour.rs

@@ -130,7 +130,7 @@ impl<TSpec: EthSpec> NetworkBehaviour for PeerManager<TSpec> {
         }
 
         // Check NAT if metrics are enabled
-        if self.network_globals.local_enr.read().udp().is_some() {
+        if self.network_globals.local_enr.read().udp4().is_some() {
             metrics::check_nat();
         }