Bump nokogiri from 1.13.6 to 1.13.9 in /docs

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] <[email protected]>

Author: dependabot[bot]

docs/Gemfile.lock

@@ -41,7 +41,6 @@ GEM
     faraday-net_http (1.0.1)
     faraday-net_http_persistent (1.1.0)
     ffi (1.15.1)
-    ffi (1.15.1-x64-mingw32)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
     github-pages (215)
@@ -222,11 +221,9 @@ GEM
       jekyll-seo-tag (~> 2.1)
     minitest (5.14.4)
     multipart-post (2.1.1)
-    nokogiri (1.13.6)
+    nokogiri (1.13.9)
       mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
-    nokogiri (1.13.6-x64-mingw32)
-      racc (~> 1.4)
     octokit (4.21.0)
       faraday (>= 0.9)
       sawyer (~> 0.8.0, >= 0.5.3)
@@ -266,7 +263,6 @@ GEM
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.7.7)
-    unf_ext (0.0.7.7-x64-mingw32)
     unicode-display_width (1.7.0)
     zeitwerk (2.4.2)