Bump html-proofer from 3.18.8 to 3.19.0
Bumps [html-proofer](https://github.com/gjtorikian/html-proofer) from 3.18.8 to 3.19.0. - [Release notes](https://github.com/gjtorikian/html-proofer/releases) - [Commits](https://github.com/gjtorikian/html-proofer/compare/v3.18.8...v3.19.0)