[PM-8872] [deps]: Update Rust crate clap_mangen to v0.2.21 (#844)

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [clap_mangen](https://togithub.com/clap-rs/clap) | build-dependencies
| patch | `0.2.20` -> `0.2.21` |

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### Release Notes

<details>
<summary>clap-rs/clap (clap_mangen)</summary>

###
[`v0.2.21`](https://togithub.com/clap-rs/clap/compare/clap_mangen-v0.2.20...clap_mangen-v0.2.21)

[Compare
Source](https://togithub.com/clap-rs/clap/compare/clap_mangen-v0.2.20...clap_mangen-v0.2.21)

</details>

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[PM-8872](https://bitwarden.atlassian.net/browse/PM-8872)

[PM-8872]:
https://bitwarden.atlassian.net/browse/PM-8872?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>