:arrow_up: Bump mkdocs-htmlproofer-plugin in /docs/mkdocs (#5057)

Bumps [mkdocs-htmlproofer-plugin](https://github.com/manuzhang/mkdocs-htmlproofer-plugin) from 1.4.0 to 1.4.1.
- [Release notes](https://github.com/manuzhang/mkdocs-htmlproofer-plugin/releases)
- [Commits](https://github.com/manuzhang/mkdocs-htmlproofer-plugin/compare/v1.4.0...v1.4.1)

---
updated-dependencies:
- dependency-name: mkdocs-htmlproofer-plugin
  dependency-version: 1.4.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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