Lock RuboCop on CI.

Author: simi

Gemfile

@@ -25,7 +25,7 @@ group :development do
   gem "rake"
   gem "rspec"
   gem "pry"
-  gem "rubocop"
+  gem "rubocop", "~> 1.70.0" if RUBY_VERSION > "3.2"
   gem "test-unit"
   gem "logger"
   # Explicitly add webrick because it has been removed from stdlib in Ruby 3.0

Gemfile.lock

@@ -187,7 +187,7 @@ DEPENDENCIES
   rackup
   rake
   rspec
-  rubocop
+  rubocop (~> 1.70.0)
   simplecov!
   test-unit
   webrick