Pull Request

Related issue

Fixes #665

What does this PR do?

• Change the type of deleted_tasks field in TaskDeletion from usize to Option<usize>
  • This should be Option<usize> since it can be null according to the API documentation

PR checklist

Please check if your PR fulfills the following requirements:

• Does this PR fix an existing issue, or have you listed the changes applied in the PR description (and why they are needed)?
• Have you read the contributing guidelines?
• Have you made sure that the title is accurate and descriptive of the changes?

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