Fix circular require of RDoc::Parser::RubyColorizer

[tompng]

Loading RubyColorizer will trigger autoload of RDoc::Parser, and require_relative 'parser/ruby'.
parser/ruby.rb shouldn't require ruby_colorizer.rb to avoid circular require.

Originally found in rake test log, but can be reproduced with:

$ ruby -W -rrdoc -Ilib -e 'p RDoc::Markup::ToHtml'
warning: loading in progress, circular require considered harmful

[matzbot]

🚀 Preview deployment available at: https://caa4c640.rdoc-6cd.pages.dev (commit: 47f155f)

[Copilot]

Pull request overview

Fixes a circular require warning triggered when autoloading RDoc::Markup::ToHtml (via require 'rdoc') by removing direct ruby_colorizer requires that caused RDoc::Parser to be autoloaded mid-load.

Changes:

• Removed ruby_colorizer requires from RDoc::Parser::Ruby and RDoc::Markup::ToHtml to break the problematic load chain.
• Added parser/ruby_colorizer loading to lib/rdoc/parser.rb so the colorizer is available when the parser is loaded.
• Updated the RubyColorizer test to rely on autoloading instead of directly requiring the colorizer.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
test/rdoc/parser/ruby_colorizer_test.rb	Stops requiring rdoc/parser/ruby_colorizer directly in tests.
lib/rdoc/parser/ruby.rb	Removes require_relative 'ruby_colorizer' to avoid circular require.
lib/rdoc/parser.rb	Loads parser/ruby_colorizer from the parser entrypoint.
lib/rdoc/markup/to_html.rb	Removes direct require of rdoc/parser/ruby_colorizer to avoid triggering circular require during autoload.

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