Note we're using the `call` method (which is equivalent to adding an ERB
file) because we were getting an error calling `render` from the `dates`
method:
```
ActionView::Base#lookup_context delegated to
view_renderer.lookup_context, but view_renderer is nil:
```
It might be because we aren't rendering the
`Adming::Budgets::DurationComponent` but just calling one method, and so
there's no view context in this case.
In this case, the duration of the budget cannot be determined, and the
application was crashing when trying to do so.
Now we're just returning `nil` as duration.
