Update rubocop requirement from ~> 1.57.2 to ~> 1.59.0

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@v1.57.2...v1.58.0)

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

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

voxpupuli-rubocop.gemspec

@@ -14,7 +14,7 @@ Gem::Specification.new do |s|
   s.required_ruby_version = '>= 2.7.0'
 
   s.add_runtime_dependency 'rake', '~> 13.0', '>= 13.0.6'
-  s.add_runtime_dependency 'rubocop', '~> 1.57.2'
+  s.add_runtime_dependency 'rubocop', '~> 1.59.0'
   s.add_runtime_dependency 'rubocop-minitest', '~> 0.33.0'
   s.add_runtime_dependency 'rubocop-performance', '~> 1.19.0'
   s.add_runtime_dependency 'rubocop-rake', '~> 0.6.0'