Remove warning messages

Gemfile

@@ -7,5 +7,5 @@ group :local_development do
   gem 'guard-rspec'
   gem 'appraisal'
   gem 'rake'
-  gem 'byebug' , platform: :mri_21
+  gem 'byebug' , platforms: [:mri_21, :mri_22, :mri_23]
 end

spec/acts_as_taggable_on/acts_as_tagger_spec.rb

@@ -72,7 +72,7 @@
         expect(@taggable.tag_list_on(:foo_boo)).to be_empty
         expect(-> {
           @tagger.tag(@taggable, with: 'this, and, that', on: :foo_boo, force: false)
-        }).to raise_error
+        }).to raise_error(RuntimeError)
       end
 
       it 'should not create the tag context on-the-fly when the default is over-ridden' do

spec/acts_as_taggable_on/tag_list_spec.rb

@@ -92,7 +92,7 @@
 
     it 'should be able to call to_s on a frozen tag list' do
       tag_list.freeze
-      expect(-> { tag_list.add('cool', 'rad,bodacious') }).to raise_error
+      expect(-> { tag_list.add('cool', 'rad,bodacious') }).to raise_error(RuntimeError)
       expect(-> { tag_list.to_s }).to_not raise_error
     end
   end