misc: remove once_cell; superseded by std::*

We now have types in the Rust standard library.
Dropping the dependency.

I found this by using the `clippy::pedantic` group.

Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com

net_util/src/tap.rs

@@ -506,11 +506,10 @@ impl AsRawFd for Tap {
 #[cfg(test)]
 mod tests {
     use std::net::Ipv4Addr;
-    use std::sync::{mpsc, Mutex};
+    use std::sync::{mpsc, LazyLock, Mutex};
     use std::time::Duration;
     use std::{str, thread};
 
-    use once_cell::sync::Lazy;
     use pnet::packet::ethernet::{EtherTypes, EthernetPacket, MutableEthernetPacket};
     use pnet::packet::ip::IpNextHeaderProtocols;
     use pnet::packet::ipv4::{Ipv4Packet, MutableIpv4Packet};
@@ -525,13 +524,14 @@ mod tests {
     static DATA_STRING: &str = "test for tap";
     static SUBNET_MASK: &str = "255.255.255.0";
 
-    // We needed to have a mutex as a global variable, so we used once_cell for testing. The main
+    // We needed to have a mutex as a global variable, so we use a once cell for testing. The main
     // potential problem, caused by tests being run in parallel by cargo, is creating different
     // TAPs and trying to associate the same address, so we hide the IP address &str behind this
     // mutex, more as a convention to remember to lock it at the very beginning of each function
     // susceptible to this issue. Another variant is to use a different IP address per function,
     // but we must remember to pick an unique one each time.
-    static TAP_IP_LOCK: Lazy<Mutex<&'static str>> = Lazy::new(|| Mutex::new("192.168.241.1"));
+    static TAP_IP_LOCK: LazyLock<Mutex<&'static str>> =
+        LazyLock::new(|| Mutex::new("192.168.241.1"));
 
     // Describes the outcomes we are currently interested in when parsing a packet (we use
     // an UDP packet for testing).