specify utf-8 encoding for pygments.rb markdown wrapper

lib/redcarpet/render/gitlab_html.rb

 class Redcarpet::Render::GitlabHTML < Redcarpet::Render::HTML
   def block_code(code, language)
     if Pygments::Lexer.find(language)
-      Pygments.highlight(code, :lexer => language)
+      Pygments.highlight(code, :lexer => language, :options => {:encoding => 'utf-8'})
     else
-      Pygments.highlight(code)
+      Pygments.highlight(code, :options => {:encoding => 'utf-8'})
     end
   end
-end
\ No newline at end of file
+end