chore: Implement latest clippy warnings (#3220)

As I do frequently, I corrected for the latest clippy warnings. This will make sure the CI won't complain in the future. We could automate this btw and maybe run the nightly version of clippy.

protocols/relay/examples/relay_v2.rs

@@ -38,12 +38,12 @@ fn main() -> Result<(), Box<dyn Error>> {
     env_logger::init();
 
     let opt = Opt::parse();
-    println!("opt: {:?}", opt);
+    println!("opt: {opt:?}");
 
     // Create a static known PeerId based on given secret
     let local_key: identity::Keypair = generate_ed25519(opt.secret_key_seed);
     let local_peer_id = PeerId::from(local_key.public());
-    println!("Local peer id: {:?}", local_peer_id);
+    println!("Local peer id: {local_peer_id:?}");
 
     let tcp_transport = tcp::async_io::Transport::default();
 
@@ -80,10 +80,10 @@ fn main() -> Result<(), Box<dyn Error>> {
         loop {
             match swarm.next().await.expect("Infinite Stream.") {
                 SwarmEvent::Behaviour(Event::Relay(event)) => {
-                    println!("{:?}", event)
+                    println!("{event:?}")
                 }
                 SwarmEvent::NewListenAddr { address, .. } => {
-                    println!("Listening on {:?}", address);
+                    println!("Listening on {address:?}");
                 }
                 _ => {}
             }