Update rubocop requirement from = 0.55 to = 1.60.1

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@v0.55.0...v1.60.1)

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

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

supermarket_sync.gemspec

@@ -36,5 +36,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'bundler', '~> 2.0'
   spec.add_development_dependency 'rake', '>= 12.3.3'
   spec.add_development_dependency 'rspec', '~> 3.0'
-  spec.add_development_dependency 'rubocop', '= 0.55'
+  spec.add_development_dependency 'rubocop', '= 1.60.1'
 end