Bump html-proofer from 3.18.6 to 3.18.8

Bumps [html-proofer](https://github.com/gjtorikian/html-proofer) from 3.18.6 to 3.18.8.
- [Release notes](https://github.com/gjtorikian/html-proofer/releases)
- [Commits](https://github.com/gjtorikian/html-proofer/compare/v3.18.6...v3.18.8)
8 jobs for dependabot/bundler/html-proofer-3.18.8 in 4 minutes and 45 seconds (queued for 5 seconds)
Status Name Job ID Coverage
  Build
passed build:latest #241160

00:01:04

passed build:production #241163

00:01:42

passed build:production:review-apps #241162

00:01:44

passed build:production:subpath #241161

00:01:52

 
  Test
passed test:htmlproofer #241164

00:01:52

passed test:htmlproofer:subpath #241165

00:01:02

 
  Review
passed review #241166
review-apps

00:00:06

passed stop_review #241167
review-apps manual

00:00:00