Upgrade to libp2p v0.50.0 (#3764)

I've needed to do this work in order to do some episub testing. 

This version of libp2p has not yet been released, so this is left as a draft for when we wish to update.

Co-authored-by: Diva M <divma@protonmail.com>

beacon_node/lighthouse_network/src/peer_manager/peerdb/client.rs

@@ -2,7 +2,7 @@
 //!
 //! Currently using identify to fingerprint.
 
-use libp2p::identify::IdentifyInfo;
+use libp2p::identify::Info as IdentifyInfo;
 use serde::Serialize;
 use strum::{AsRefStr, EnumIter, IntoStaticStr};