Merge pull request #2456 from rspec/update-redcarpet

Update redcarpet

Author: JonRowe

Gemfile

@@ -10,7 +10,7 @@ gem 'yard', '~> 0.9.24', require: false
 
 group :documentation do
   gem 'github-markup', '~> 3.0.3'
-  gem 'redcarpet', '~> 3.4.0', platforms: [:ruby]
+  gem 'redcarpet', '~> 3.5.1', platforms: [:ruby]
   gem 'relish', '~> 0.7.1'
 end