libp2p-metrics 0.3.0

# 0.3.0 [2022-01-27]

- Update dependencies.

- Migrate to Rust edition 2021 (see [PR 2339]).

[PR 2339]: https://github.com/libp2p/rust-libp2p/pull/2339

# 0.2.0 [2021-11-16]

- Include gossipsub metrics (see [PR 2316]).

- Update dependencies.

[PR 2316]: https://github.com/libp2p/rust-libp2p/pull/2316

# 0.1.0 [2021-11-01]

- Add initial version.