build(deps): bump rubocop constrain from 0.80.1 to ~> 1.12

The version `1.12.1` was the last to officialy support `Ruby 2.4`

Author: nicolastemciuc

cose.gemspec

@@ -39,6 +39,6 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "byebug", "~> 11.0"
   spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "rspec", "~> 3.8"
-  spec.add_development_dependency "rubocop", "0.80.1"
+  spec.add_development_dependency "rubocop", "~> 1.12"
   spec.add_development_dependency "rubocop-performance", "~> 1.4"
 end