Update RuboCop version constraint to ~> 1.64

The `either_consistent` configuration introduced in the previous commit
was added to RuboCop in v1.64, requiring this change.

See: https://github.com/rubocop/rubocop/releases/tag/v1.64.0

Gemfile.lock

@@ -2,7 +2,7 @@ PATH
   remote: .
   specs:
     rubocop-cargosense (2.0.0)
-      rubocop (~> 1.61)
+      rubocop (~> 1.64)
       rubocop-capybara (~> 2.20)
       rubocop-factory_bot (~> 2.26.1)
       rubocop-performance (~> 1.20)

rubocop-cargosense.gemspec

@@ -25,7 +25,7 @@ Gem::Specification.new do |spec|
     "source_code_uri" => "#{spec.homepage}/tree/v#{spec.version}"
   }
 
-  spec.add_dependency "rubocop", "~> 1.61"
+  spec.add_dependency "rubocop", "~> 1.64"
   spec.add_dependency "rubocop-capybara", "~> 2.20"
   spec.add_dependency "rubocop-factory_bot", "~> 2.26.1"
   spec.add_dependency "rubocop-performance", "~> 1.20"