Update libp2p requirement from 0.22.0 to 0.39.1

Updates the requirements on [libp2p](https://github.com/libp2p/rust-libp2p) to permit the latest version.
- [Release notes](https://github.com/libp2p/rust-libp2p/releases)
- [Changelog](https://github.com/libp2p/rust-libp2p/blob/master/CHANGELOG.md)
- [Commits](libp2p/rust-libp2p@v0.22.0...v0.39.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

artillery-core/Cargo.toml

@@ -25,7 +25,7 @@ rand = "0.7.3"
 mio = { version = "0.7.0", features = ["os-poll", "udp"] }
 futures = "0.3.5"
 pin-utils = "0.1.0"
-libp2p = { version = "0.22.0", default-features = false, features = ["mdns"] }
+libp2p = { version = "0.39.1", default-features = false, features = ["mdns"] }
 bastion-executor = "0.3.5"
 lightproc = "0.3.5"
 crossbeam-channel = "0.4.2"