chore(deps): update rust crate tokio-util to v0.7.12 (#119)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [tokio-util](https://tokio.rs)
([source](https://redirect.github.com/tokio-rs/tokio)) |
dev-dependencies | patch | `0.7.11` -> `0.7.12` |

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### Release Notes

<details>
<summary>tokio-rs/tokio (tokio-util)</summary>

###
[`v0.7.12`](https://redirect.github.com/tokio-rs/tokio/compare/tokio-util-0.7.11...tokio-util-0.7.12)

[Compare
Source](https://redirect.github.com/tokio-rs/tokio/compare/tokio-util-0.7.11...tokio-util-0.7.12)

</details>

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