Bump nokogiri from 1.13.6 to 1.13.9 in /docs (#1537)

docs/Gemfile.lock

@@ -1,7 +1,7 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (6.0.3.2)
+    activesupport (6.0.6)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 0.7, < 2)
       minitest (~> 5.1)
@@ -80,7 +80,7 @@ GEM
       octokit (~> 4.0)
       public_suffix (~> 3.0)
       typhoeus (~> 1.3)
-    html-pipeline (2.13.0)
+    html-pipeline (2.14.3)
       activesupport (>= 2)
       nokogiri (>= 1.4)
     http_parser.rb (0.6.0)
@@ -193,7 +193,7 @@ GEM
       jekyll (>= 3.0, < 5.0)
     kramdown (1.17.0)
     liquid (4.0.3)
-    listen (3.2.1)
+    listen (3.7.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
@@ -202,9 +202,9 @@ GEM
       jekyll (>= 3.5, < 5.0)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
-    minitest (5.14.1)
+    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 (4.18.0)
@@ -220,7 +220,7 @@ GEM
     rouge (3.19.0)
     ruby-enum (0.8.0)
       i18n
-    rubyzip (2.3.0)
+    rubyzip (2.3.2)
     safe_yaml (1.0.5)
     sass (3.7.4)
       sass-listen (~> 4.0.0)
@@ -243,7 +243,7 @@ GEM
       unf_ext
     unf_ext (0.0.7.7)
     unicode-display_width (1.7.0)
-    zeitwerk (2.4.0)
+    zeitwerk (2.6.1)
 
 PLATFORMS
   ruby