Fix 8.0.3 documentation generation by updating sdoc to 2.6.4

Author: rafaelfranca

lib/generators/release.rb

@@ -25,7 +25,7 @@ def before_generation
       elsif version_number == '8.0.3'
         # sdoc 2.6.2 has a bug with RDoc
         patch 'Gemfile' do |contents|
-          contents.sub(/gem "sdoc".*/, "gem \"sdoc\", \"~> 2.6.3\"")
+          contents.sub(/gem "sdoc".*/, "gem \"sdoc\", \"~> 2.6.4\"")
         end
       elsif version_number >= '5.1.2' && version_number <= '5.1.4'
         patch 'guides/source/documents.yaml' do |contents|

test/fixtures/releases/v8.0.3/Gemfile.expected

@@ -64,7 +64,7 @@ group :mdl do
 end
 
 group :doc do
-  gem "sdoc", "~> 2.6.3"
+  gem "sdoc", "~> 2.6.4"
   gem "redcarpet", "~> 3.2.3", platforms: :ruby
   gem "w3c_validators", "~> 1.3.6"
   gem "rouge"