Bump nokogiri from 1.6.2.1 to 1.6.8.1

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.6.2.1 to 1.6.8.1.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/main/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.6.2.1...v1.6.8.1)

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

Author: dependabot[bot]

Gemfile

@@ -7,7 +7,7 @@ gem 'coderay'
 gem 'kramdown', '~> 0.13.2'
 gem 'mime-types', '~> 1.16'
 gem 'nanoc', '~> 3.7'
-gem 'nokogiri', '~> 1.6.0'
+gem 'nokogiri', '~> 1.6.8'
 gem 'rouge', '~> 1.4'
 gem 'rake', '~> 0.9.2'
 gem 'thin'

Gemfile.lock

@@ -41,11 +41,11 @@ GEM
     mercenary (0.3.3)
     method_source (0.8.2)
     mime-types (1.25.1)
-    mini_portile (0.6.0)
+    mini_portile2 (2.1.0)
     nanoc (3.7.1)
       cri (~> 2.3)
-    nokogiri (1.6.2.1)
-      mini_portile (= 0.6.0)
+    nokogiri (1.6.8.1)
+      mini_portile2 (~> 2.1.0)
     pry (0.10.0)
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
@@ -81,7 +81,7 @@ DEPENDENCIES
   kramdown (~> 0.13.2)
   mime-types (~> 1.16)
   nanoc (~> 3.7)
-  nokogiri (~> 1.6.0)
+  nokogiri (~> 1.6.8)
   rake (~> 0.9.2)
   rouge (~> 1.4)
   thin