chore(deps): bump nokogiri from 1.18.4 to 1.18.8 in /slate-docs (#520)

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.18.4 to 1.18.8.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/main/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.18.4...v1.18.8)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-version: 1.18.8
  dependency-type: direct:production
...

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

Author: dependabot[bot]

slate-docs/Gemfile

@@ -8,6 +8,6 @@ gem 'middleman-autoprefixer', '~> 3.0'
 gem 'middleman-sprockets', '~> 4.1'
 gem 'rouge', '~> 3.21'
 gem 'redcarpet', '~> 3.6.0'
-gem 'nokogiri', '~> 1.18.4'
+gem 'nokogiri', '~> 1.18.8'
 gem 'sass'
 gem 'webrick'

slate-docs/Gemfile.lock

@@ -81,7 +81,7 @@ GEM
       rouge (~> 3.2)
     mini_portile2 (2.8.8)
     minitest (5.20.0)
-    nokogiri (1.18.4)
+    nokogiri (1.18.8)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     padrino-helpers (0.15.2)
@@ -130,7 +130,7 @@ DEPENDENCIES
   middleman-autoprefixer (~> 3.0)
   middleman-sprockets (~> 4.1)
   middleman-syntax (~> 3.2)
-  nokogiri (~> 1.18.4)
+  nokogiri (~> 1.18.8)
   redcarpet (~> 3.6.0)
   rouge (~> 3.21)
   sass