Bump html-proofer from 3.19.1 to 3.19.2

Bumps [html-proofer](https://github.com/gjtorikian/html-proofer) from 3.19.1 to 3.19.2.
- [Release notes](https://github.com/gjtorikian/html-proofer/releases)
- [Commits](https://github.com/gjtorikian/html-proofer/compare/v3.19.1...v3.19.2)

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

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

Gemfile.lock

@@ -44,19 +44,19 @@ GEM
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
     erubi (1.10.0)
-    ethon (0.13.0)
+    ethon (0.14.0)
       ffi (>= 1.15.0)
     eventmachine (1.2.7)
     execjs (2.7.0)
     faraday (1.0.1)
       multipart-post (>= 1.2, < 3)
-    ffi (1.15.0)
+    ffi (1.15.3)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
     html-pipeline (2.13.0)
       activesupport (>= 2)
       nokogiri (>= 1.4)
-    html-proofer (3.19.1)
+    html-proofer (3.19.2)
       addressable (~> 2.3)
       mercenary (~> 0.3)
       nokogumbo (~> 2.0)