2.1.209

Update html-proofer requirement from 3.19.4 to 4.1.0 (#288)

Updates the requirements on [html-proofer](https://github.com/gjtorikian/html-proofer) to permit the latest version.
- [Release notes](https://github.com/gjtorikian/html-proofer/releases)
- [Changelog](https://github.com/gjtorikian/html-proofer/blob/main/CHANGELOG.md)
- [Commits](https://github.com/gjtorikian/html-proofer/compare/v3.19.4...v4.1.0)

---
updated-dependencies:
- dependency-name: html-proofer
  dependency-type: direct:production
...

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