Update io-lifetimes, cap-std, and rsix (#3269)

- Fixes for compiling on OpenBSD

 - io-lifetimes 0.3.0 has an option (io_lifetimes_use_std, which is off
   by default) for testing the `io_safety` feature in Rust nightly.

crates/wasi-common/tokio/src/lib.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(io_lifetimes_use_std, feature(io_safety))]
+
 mod dir;
 mod file;
 pub mod sched;