Update rouge requirement from ~> 3.1 to ~> 4.1

Updates the requirements on [rouge](https://github.com/rouge-ruby/rouge) to permit the latest version.
- [Release notes](https://github.com/rouge-ruby/rouge/releases)
- [Changelog](https://github.com/rouge-ruby/rouge/blob/master/CHANGELOG.md)
- [Commits](rouge-ruby/rouge@v3.1.0...v4.1.2)

---
updated-dependencies:
- dependency-name: rouge
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Gemfile

@@ -38,5 +38,5 @@ group :test do
   gem "nokogiri", "~> 1.13"
 
   gem "minitest-focus", "~> 1.1"
-  gem "rouge", "~> 3.1", require: false
+  gem "rouge", "~> 4.1", require: false
 end