Bump libp2p to address inconsistency in mesh peer tracking (#2493)

## Issue Addressed

- Resolves #2457
- Resolves #2443

## Proposed Changes

Target the (presently unreleased) head of `libp2p/rust-libp2p:master` in order to obtain the fix from https://github.com/libp2p/rust-libp2p/pull/2175.

Additionally:

- `libsecp256k1` needed to be upgraded to satisfy the new version of `libp2p`.
- There were also a handful of minor changes to `eth2_libp2p` to suit some interface changes.
- Two `cargo audit --ignore` flags were remove due to libp2p upgrades.

## Additional Info
 
 NA

beacon_node/eth2_libp2p/Cargo.toml

@@ -42,13 +42,15 @@ regex = "1.3.9"
 strum = { version = "0.20", features = ["derive"] }
 superstruct = "0.2.0"
 
+# TODO: remove the rev-reference and go back to release versions once there is a release that
+# includes the following PR:
+#
+# https://github.com/libp2p/rust-libp2p/pull/2175
 [dependencies.libp2p]
 #version = "0.39.1"
 #default-features = false
-# TODO: Update once https://github.com/libp2p/rust-libp2p/pull/2103 and 
-# https://github.com/libp2p/rust-libp2p/pull/2137 are merged upstream.
-git = "https://github.com/sigp/rust-libp2p"
-rev = "75fd53ec5407a58ae1ff600fd1c68ea49079364a"
+git = "https://github.com/libp2p/rust-libp2p"
+rev = "ce23cbe76a0382b6fcb0e49f1b2612df86f6465d"
 features = ["websocket", "identify", "mplex", "yamux", "noise", "gossipsub", "dns-tokio", "tcp-tokio"]
 
 [dev-dependencies]