Update rubocop requirement from ~> 1.53.0 to ~> 1.56.4

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@v1.53.0...v1.56.4)

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

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

makara.gemspec

@@ -26,7 +26,7 @@ Gem::Specification.new do |gem|
   gem.add_development_dependency "rake", "~> 13.0"
   gem.add_development_dependency "rspec", "~> 3.9"
   gem.add_development_dependency "timecop"
-  gem.add_development_dependency "rubocop", "~> 1.53.0"
+  gem.add_development_dependency "rubocop", "~> 1.56.4"
 
   if RUBY_ENGINE == "jruby"
     gem.add_development_dependency "activerecord-jdbcmysql-adapter"