Fix WASM build for WebSocket

[quaintsorcery]

I ran into a WASM build error with aeronet_websocket.
Steps to replicate:

• cargo update
• cargo build --target wasm32-unknown-unknown --features client --example websocket_client

Removing the type hint fixes the build error, works with not updated Cargo.lock too.

[aecsocket]

Yep looks like my CI didn't catch it because it's using an old lockfile. Possibly a breaking change in wasm-bindgen, or did I miss something?

[aecsocket]

Will release a v0.16.0 to fix this, since I also have a breaking change in main (skipping v0.15 because aeronet_replicon already has a published 0.15)