Bump nokogiri from 1.13.6 to 1.13.9 in /docs (#486)

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.13.6 to 1.13.9.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/main/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.13.6...v1.13.9)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-type: indirect
...

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

docs/Gemfile.lock

@@ -1,14 +1,14 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (6.0.3.4)
+    activesupport (6.0.6)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 0.7, < 2)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
       zeitwerk (~> 2.2, >= 2.2.2)
-    addressable (2.8.0)
-      public_suffix (>= 2.0.2, < 5.0)
+    addressable (2.8.1)
+      public_suffix (>= 2.0.2, < 6.0)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
@@ -82,7 +82,7 @@ GEM
       octokit (~> 4.0)
       public_suffix (~> 3.0)
       typhoeus (~> 1.3)
-    html-pipeline (2.14.0)
+    html-pipeline (2.14.3)
       activesupport (>= 2)
       nokogiri (>= 1.4)
     http_parser.rb (0.6.0)
@@ -203,7 +203,7 @@ GEM
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
     liquid (4.0.3)
-    listen (3.3.0)
+    listen (3.7.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
@@ -212,9 +212,9 @@ GEM
       jekyll (>= 3.5, < 5.0)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
-    minitest (5.14.2)
+    minitest (5.16.3)
     multipart-post (2.1.1)
-    nokogiri (1.13.6)
+    nokogiri (1.13.9)
       mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
     octokit (4.19.0)
@@ -256,7 +256,7 @@ GEM
       unf_ext
     unf_ext (0.0.7.7)
     unicode-display_width (1.7.0)
-    zeitwerk (2.4.1)
+    zeitwerk (2.6.1)
 
 PLATFORMS
   ruby