gems: update rubocop requirement from ~> 1.65.0 to ~> 1.66.0

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@v1.65.0...v1.66.0)

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

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

dyndnsd.gemspec

@@ -42,7 +42,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rack-test'
   s.add_development_dependency 'rake'
   s.add_development_dependency 'rspec'
-  s.add_development_dependency 'rubocop', '~> 1.65.0'
+  s.add_development_dependency 'rubocop', '~> 1.66.0'
   s.add_development_dependency 'rubocop-rake', '~> 0.6.0'
   s.add_development_dependency 'rubocop-rspec', '~> 3.0.1'
   s.add_development_dependency 'solargraph', '~> 0.49.0'