Log Message:
www/ruby-rack-contrib: update to 2.4.0

2.4.0 (2023-10-14)

* Refer to github, not Rubyforge [ci skip]
* Support Rack 3 (#187)
* Rack::JSONBodyParser: rescue all parser exceptions (#184)
* Prefer to use version constant for release management.
* Don't bother testing on Ruby 2.2 as it's failing and way EOL.