Bump nokogiri from 1.10.9 to 1.13.4

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.10.9 to 1.13.4.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/v1.13.4/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.10.9...v1.13.4)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile

@@ -8,5 +8,5 @@ gem 'middleman-autoprefixer', '~> 2.7'
 gem 'middleman-sprockets', '~> 4.1'
 gem 'rouge', '~> 3.20'
 gem 'redcarpet', '~> 3.5.0'
-gem 'nokogiri', '~> 1.10.8'
+gem 'nokogiri', '~> 1.13.4'
 gem 'sass'

Gemfile.lock

@@ -77,10 +77,11 @@ GEM
     middleman-syntax (3.2.0)
       middleman-core (>= 3.2)
       rouge (~> 3.2)
-    mini_portile2 (2.4.0)
+    mini_portile2 (2.8.0)
     minitest (5.14.1)
-    nokogiri (1.10.9)
-      mini_portile2 (~> 2.4.0)
+    nokogiri (1.13.4)
+      mini_portile2 (~> 2.8.0)
+      racc (~> 1.4)
     padrino-helpers (0.13.3.4)
       i18n (~> 0.6, >= 0.6.7)
       padrino-support (= 0.13.3.4)
@@ -89,6 +90,7 @@ GEM
       activesupport (>= 3.1)
     parallel (1.19.2)
     public_suffix (4.0.5)
+    racc (1.6.0)
     rack (2.2.3)
     rb-fsevent (0.10.4)
     rb-inotify (0.10.1)
@@ -124,7 +126,7 @@ DEPENDENCIES
   middleman-autoprefixer (~> 2.7)
   middleman-sprockets (~> 4.1)
   middleman-syntax (~> 3.2)
-  nokogiri (~> 1.10.8)
+  nokogiri (~> 1.13.4)
   redcarpet (~> 3.5.0)
   rouge (~> 3.20)
   sass