build(deps-dev): bump github-pages from 218 to 219 in /docs

Bumps [github-pages](https://github.com/github/pages-gem) from 218 to 219.
- [Release notes](https://github.com/github/pages-gem/releases)
- [Commits](https://github.com/github/pages-gem/compare/v218...v219)

---
updated-dependencies:
- dependency-name: github-pages
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

docs/Gemfile.lock

@@ -26,7 +26,7 @@ GEM
       ffi (>= 1.15.0)
     eventmachine (1.2.7)
     execjs (2.8.1)
-    faraday (1.7.0)
+    faraday (1.7.1)
       faraday-em_http (~> 1.0)
       faraday-em_synchrony (~> 1.0)
       faraday-excon (~> 1.1)
@@ -48,8 +48,8 @@ GEM
     ffi (1.15.3)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
-    github-pages (218)
-      github-pages-health-check (= 1.17.2)
+    github-pages (219)
+      github-pages-health-check (= 1.17.7)
       jekyll (= 3.9.0)
       jekyll-avatar (= 0.7.0)
       jekyll-coffeescript (= 1.1.1)
@@ -92,11 +92,11 @@ GEM
       nokogiri (>= 1.10.4, < 2.0)
       rouge (= 3.26.0)
       terminal-table (~> 1.4)
-    github-pages-health-check (1.17.2)
+    github-pages-health-check (1.17.7)
       addressable (~> 2.3)
       dnsruby (~> 1.60)
       octokit (~> 4.0)
-      public_suffix (>= 2.0.2, < 5.0)
+      public_suffix (>= 3.0, < 5.0)
       typhoeus (~> 1.3)
     html-pipeline (2.14.0)
       activesupport (>= 2)
@@ -234,7 +234,7 @@ GEM
       jekyll-seo-tag (~> 2.1)
     minitest (5.14.4)
     multipart-post (2.1.1)
-    nokogiri (1.12.3)
+    nokogiri (1.12.4)
       mini_portile2 (~> 2.6.1)
       racc (~> 1.4)
     nokogumbo (2.0.5)