CHANGELOG.md: Fix link to yamux changelog
- `libp2p-websocket`
- [v0.33.0](transports/websocket/CHANGELOG.md#0330-2022-01-27)
- `libp2p-yamux`
- - [v0.35.0](transports/yamux/CHANGELOG.md#0350-2022-01-27)
+ - [v0.35.0](muxers/yamux/CHANGELOG.md#0350-2022-01-27)
- Migrate to Rust edition 2021 (see [PR 2339]).
