Add rspec-its

Author: sue445

rspec-parameterized-core.gemspec

@@ -43,6 +43,7 @@ I was inspired by [udzura's mock](https://gist.github.com/1881139).}
   spec.add_dependency "prism"
 
   spec.add_development_dependency "rake", ">= 12.0.0"
+  spec.add_development_dependency "rspec-its"
 
   # For more information and examples about making a new gem, check out our
   # guide at: https://bundler.io/guides/creating_gem.html

spec/spec_helper.rb

@@ -1,5 +1,7 @@
 require 'rspec-parameterized-core'
 
+require 'rspec/its'
+
 RSpec.configure do |config|
   config.treat_symbols_as_metadata_keys_with_true_values = true
   config.run_all_when_everything_filtered = true