Bump clap_mangen from 0.2.20 to 0.2.21

Bumps [clap_mangen](https://github.com/clap-rs/clap) from 0.2.20 to 0.2.21.
- [Release notes](https://github.com/clap-rs/clap/releases)
- [Changelog](https://github.com/clap-rs/clap/blob/master/CHANGELOG.md)
- [Commits](https://github.com/clap-rs/clap/compare/clap_mangen-v0.2.20...clap_mangen-v0.2.21)

---
updated-dependencies:
- dependency-name: clap_mangen
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.lock

@@ -128,9 +128,9 @@ checksum = "98cc8fbded0c607b7ba9dd60cd98df59af97e84d24e49c8557331cfc26d301ce"
 
 [[package]]
 name = "clap_mangen"
-version = "0.2.20"
+version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e1dd95b5ebb5c1c54581dd6346f3ed6a79a3eef95dd372fc2ac13d535535300e"
+checksum = "74b70fc13e60c0e1d490dc50eb73a749be6d81f4ef03783df1d9b7b0c62bc937"
 dependencies = [
  "clap",
  "roff",