Fix Ci::Build#artifacts_expire_in= when assigning invalid duration

spec/models/build_spec.rb

@@ -474,7 +474,7 @@ describe Ci::Build, models: true do
     end
 
     it 'when assigning invalid duration' do
-      expect { build.artifacts_expire_in = '7 elephants' }.not_to raise_error
+      expect { build.artifacts_expire_in = '7 elephants' }.to raise_error(ChronicDuration::DurationParseError)
       is_expected.to be_nil
     end