Remove by qualifier in neg. #change expectation

No longer supported.

Signed-off-by: Alex Coles <alex@alexbcoles.com>

spec/models/work_package/work_package_acts_as_journalized_spec.rb

@@ -73,7 +73,7 @@ describe WorkPackage, type: :model do
       end
 
       it 'is not created' do
-        expect { work_package.save! }.to_not change { work_package.journals.length }.by(1)
+        expect { work_package.save! }.to_not change { work_package.journals.length }
       end
     end