build(deps-dev): bump html-proofer from 3.19.2 to 3.19.3 in /docs

Bumps [html-proofer](https://github.com/gjtorikian/html-proofer) from 3.19.2 to 3.19.3.
- [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/v3.19.2...v3.19.3)

---
updated-dependencies:
- dependency-name: html-proofer
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

docs/Gemfile.lock

@@ -103,10 +103,10 @@ GEM
     html-pipeline (2.14.0)
       activesupport (>= 2)
       nokogiri (>= 1.4)
-    html-proofer (3.19.2)
+    html-proofer (3.19.3)
       addressable (~> 2.3)
       mercenary (~> 0.3)
-      nokogumbo (~> 2.0)
+      nokogiri (~> 1.12)
       parallel (~> 1.3)
       rainbow (~> 3.0)
       typhoeus (~> 1.3)
@@ -250,8 +250,6 @@ GEM
     nokogiri (1.12.5)
       mini_portile2 (~> 2.6.1)
       racc (~> 1.4)
-    nokogumbo (2.0.5)
-      nokogiri (~> 1.8, >= 1.8.4)
     octokit (4.21.0)
       faraday (>= 0.9)
       sawyer (~> 0.8.0, >= 0.5.3)