Update rouge requirement from 4.6.0 to 4.6.1 (#94)

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@v4.6.0...v4.6.1)

---
updated-dependencies:
- dependency-name: rouge
  dependency-version: 4.6.1
  dependency-type: direct:production
...

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Author: dependabot[bot]

Gemfile

@@ -17,4 +17,4 @@ gem 'epubcheck-ruby', '5.3.0.0'
 gem 'html-proofer', '5.0.10'
 gem 'kindlegen', '3.1.1'
 
-gem 'rouge', '4.6.0'
+gem 'rouge', '4.6.1'