Drop support for older versions of Rouge (#6978)

Merge pull request 6978

lib/jekyll/converters/markdown/redcarpet_parser.rb

@@ -57,7 +57,8 @@ class Jekyll::Converters::Markdown::RedcarpetParser
 
     protected
     def rouge_formatter(_lexer)
-      Jekyll::Utils::Rouge.html_formatter(:wrap => false)
+      require "rouge"
+      ::Rouge::Formatters::HTMLLegacy.new(:wrap => false)
     end
   end
 

lib/jekyll/tags/highlight.rb

@@ -112,7 +112,8 @@ MSG
       end
 
       def render_rouge(code)
-        formatter = Jekyll::Utils::Rouge.html_formatter(
+        require "rouge"
+        formatter = ::Rouge::Formatters::HTMLLegacy.new(
           :line_numbers => @highlight_options[:linenos],
           :wrap         => false,
           :css_class    => "highlight",

lib/jekyll/utils.rb

@@ -7,7 +7,6 @@ module Jekyll
     autoload :Exec, "jekyll/utils/exec"
     autoload :Internet, "jekyll/utils/internet"
     autoload :Platforms, "jekyll/utils/platforms"
-    autoload :Rouge, "jekyll/utils/rouge"
     autoload :ThreadEvent, "jekyll/utils/thread_event"
     autoload :WinTZ, "jekyll/utils/win_tz"
 

lib/jekyll/utils/rouge.rb

@@ -1,22 +0,0 @@
-# frozen_string_literal: true
-
-Jekyll::External.require_with_graceful_fail("rouge")
-
-module Jekyll
-  module Utils
-    module Rouge
-
-      def self.html_formatter(*args)
-        if old_api?
-          ::Rouge::Formatters::HTML.new(*args)
-        else
-          ::Rouge::Formatters::HTMLLegacy.new(*args)
-        end
-      end
-
-      def self.old_api?
-        ::Rouge.version.to_s < "2"
-      end
-    end
-  end
-end