Create/assign a to-do automatically based on a status change Merged

In order to have enforced approval process, it would be great to have a to-do created and assigned to a user when the status is changed to an approval status.

We want to add approval steps to workflows to prevent features from being added to a release without approval from a manager. I see how to set up custom workflow statuses, but I don't see how to add an approval stage that can be enforced.