Warning about costs not in newsletter if event price = 0
One-sentence description
The warning about the costs and registration/un-registration deadline is not shown when the price of the event is 0.
Current behaviour / Reproducing the bug
- Add an event without a price
- The 'Show warnings about costs' checkbox is checked
- Show preview of the newsletter
- The warning is not in the newsletter
Expected behaviour
The warning should be there if the checkbox is checked