chore(deps): bump redcarpet from 3.5.0 to 3.5.1 in /slate-docs (#160)

Bumps [redcarpet](https://github.com/vmg/redcarpet) from 3.5.0 to 3.5.1.
- [Release notes](https://github.com/vmg/redcarpet/releases)
- [Changelog](https://github.com/vmg/redcarpet/blob/master/CHANGELOG.md)
- [Commits](vmg/redcarpet@v3.5.0...v3.5.1)

slate-docs/Gemfile

@@ -7,6 +7,6 @@ gem 'middleman-syntax', '~> 3.2'
 gem 'middleman-autoprefixer', '~> 2.7'
 gem 'middleman-sprockets', '~> 4.1'
 gem 'rouge', '~> 3.20'
-gem 'redcarpet', '~> 3.5.0'
+gem 'redcarpet', '~> 3.5.1'
 gem 'nokogiri', '~> 1.10.8'
 gem 'sass'

slate-docs/Gemfile.lock

@@ -93,7 +93,7 @@ GEM
     rb-fsevent (0.10.4)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    redcarpet (3.5.0)
+    redcarpet (3.5.1)
     rexml (3.2.4)
     rouge (3.20.0)
     sass (3.7.4)
@@ -125,7 +125,7 @@ DEPENDENCIES
   middleman-sprockets (~> 4.1)
   middleman-syntax (~> 3.2)
   nokogiri (~> 1.10.8)
-  redcarpet (~> 3.5.0)
+  redcarpet (~> 3.5.1)
   rouge (~> 3.20)
   sass