build(deps): update rubocop requirement from < 1.27 to < 1.28

Updates the requirements on [rubocop](https://github.com/rubocop/rubocop) to permit the latest version.
- [Release notes](https://github.com/rubocop/rubocop/releases)
- [Changelog](https://github.com/rubocop/rubocop/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop@v0.0.0...v1.27.0)

---
updated-dependencies:
- dependency-name: rubocop
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile

@@ -7,7 +7,7 @@ gem 'inch', '~> 0.8'
 gem 'pry', '~> 0.14.1'
 gem 'rake', ['>= 12.3.3', '~> 13.0']
 gem 'rspec', '~> 3'
-gem 'rubocop', '< 1.27'
+gem 'rubocop', '< 1.28'
 gem 'rubocop-rake', '~> 0'
 gem 'rubocop-rspec', '~> 2'
 gem 'simplecov', '~> 0.18'