Fix clippy lint violations (#242)

Author: tottoto

src/host.rs

@@ -426,7 +426,7 @@ impl Tcp {
                 // connection refused on the client.
                 if let Some(b) = self.binds.get_mut(&dst.port()) {
                     if b.deque.len() == self.server_socket_capacity {
-                        panic!("{} server socket buffer full", dst);
+                        panic!("{dst} server socket buffer full");
                     }
 
                     if matches(b.bind_addr, dst) {

src/net/udp.rs

@@ -636,7 +636,7 @@ where
     }
 
     if interface.is_ipv4() != addr.is_ipv4() {
-        panic!("ip version mismatch: {:?} host: {:?}", interface, addr)
+        panic!("ip version mismatch: {interface:?} host: {addr:?}")
     }
 
     Ok(())

src/sim.rs

@@ -740,7 +740,7 @@ mod test {
                     let udp_socket =
                         UdpSocket::bind((IpAddr::V4(Ipv4Addr::UNSPECIFIED), 1234)).await?;
                     udp_socket
-                        .send_to(&[42], format!("{}:1234", host_b))
+                        .send_to(&[42], format!("{host_b}:1234"))
                         .await
                         .expect("sending packet should appear to work, even if partitioned");
 
@@ -765,7 +765,7 @@ mod test {
                     let udp_socket =
                         UdpSocket::bind((IpAddr::V4(Ipv4Addr::UNSPECIFIED), 1234)).await?;
                     udp_socket
-                        .send_to(&[42], format!("{}:1234", host_a))
+                        .send_to(&[42], format!("{host_a}:1234"))
                         .await
                         .expect("sending packet should work");