[PM-8872] [deps]: Update Rust crate clap_mangen to v0.2.21

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
clap_mangen	build-dependencies	patch	0.2.20 -> 0.2.21

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Release Notes

clap-rs/clap (clap_mangen)

### [`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)

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Configuration

📅 Schedule: Branch creation - "every 2nd week starting on the 2 week of the year before 4am on Monday" (UTC), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

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• [ ] If you want to rebase/retry this PR, check this box

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This PR has been generated by Mend Renovate. View repository job log here.

PM-8872

[bitwarden-bot]

Internal tracking:

• ID: PM-8872
• Link: https://bitwarden.atlassian.net/browse/PM-8872

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 60.07%. Comparing base (e4e298b) to head (2157e4c).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #844 +/- ## ======================================= Coverage 60.07% 60.07% ======================================= Files 188 188 Lines 12254 12254 ======================================= Hits 7362 7362 Misses 4892 4892 ```

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