Update criterion requirement from 0.4 to 0.6

Cargo.toml

@@ -44,7 +44,7 @@ windows-sys = { version = "0.60.0", features = ["Win32_Foundation"] }
 async-channel = "2.0.0"
 async-net = "2.0.0"
 blocking = "1"
-criterion = { version = "0.4", default-features = false, features = ["cargo_bench_support"] }
+criterion = { version = "0.6", default-features = false, features = ["cargo_bench_support"] }
 getrandom = "0.3"
 signal-hook = "0.3"
 tempfile = "3"

benches/io.rs

@@ -1,8 +1,11 @@
 //! Benchmarks for a variety of I/O operations.
 
+#![allow(clippy::incompatible_msrv)] // false positive: https://github.com/rust-lang/rust-clippy/issues/12257#issuecomment-2093667187
+
 use async_io::Async;
-use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use criterion::{criterion_group, criterion_main, Criterion};
 use futures_lite::{future, prelude::*};
+use std::hint::black_box;
 use std::net::{Ipv4Addr, SocketAddr, TcpListener, TcpStream, UdpSocket};
 
 /// Block on a future, either using the I/O driver or simple parking.

benches/timer.rs

@@ -1,8 +1,11 @@
 //! Benchmarks for registering timers.
 
+#![allow(clippy::incompatible_msrv)] // false positive: https://github.com/rust-lang/rust-clippy/issues/12257#issuecomment-2093667187
+
 use async_io::Timer;
-use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use criterion::{criterion_group, criterion_main, Criterion};
 use futures_lite::future;
+use std::hint::black_box;
 use std::time::Duration;
 
 /// Create a new `Timer` and poll it once to register it into the timer wheel.