add :Time to yaml_column_permitted_classes

To solve the following error
```ruby
     Failure/Error: expect(oc.versions.last.reify.name).to eq "Original"

     Psych::DisallowedClass:
       Tried to load unspecified class: Time
```

config/application.rb

@@ -227,7 +227,7 @@ module ::Reporting; end
     config.action_view.form_with_generates_remote_forms = false
     config.active_record.cache_versioning = false
     config.active_record.has_many_inversing = false
-    config.active_record.yaml_column_permitted_classes = [BigDecimal, Symbol, ActiveSupport::SafeBuffer]
+    config.active_record.yaml_column_permitted_classes = [BigDecimal, Symbol, ActiveSupport::SafeBuffer, Time]
 
     config.active_support.escape_html_entities_in_json = true