API update

Added the following properties to the request body for PATCH /tasks/:taskld:

• title – Lets you update the title of the task.
• start_date – Sets the start date of the task in ISO 8601 format.
• due_at – Sets the due date for the task in ISO 8601 format.
• campaign_id – Lets you link the task to a campaign.
• workflow_id – Lets you update the workflow associated with the task.