cpal 0.18.1

A quick follow-up to 0.18.0 primarily to fix the docs.rs build failure.

• docs.rs: Excluded pipewire, whose system dependency isn't available in that sandboxed build environment.
• WASM: Fixed the audioworklet feature failing to compile on wasm32-wasip1 and other non-browser wasm32 targets.

No API or behavioral changes.

Links

• https://crates.io/crates/cpal
• https://docs.rs/cpal/0.18.1
• https://github.com/RustAudio/cpal/releases/tag/v0.18.1
• https://github.com/RustAudio/cpal/blob/v0.18.1/CHANGELOG.md