Update html-proofer requirement from ~> 3.18 to ~> 5.0

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](gjtorikian/html-proofer@v3.18.0...v5.0.7)

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

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

Gemfile

@@ -5,7 +5,7 @@ source "https://rubygems.org"
 gem "jekyll-theme-chirpy", "~> 6.5", ">= 6.5.5"
 
 group :test do
-  gem "html-proofer", "~> 4.4"
+  gem "html-proofer", "~> 5.0"
 end
 
 # Windows and JRuby does not include zoneinfo files, so bundle the tzinfo-data gem