Fix: due dates shift by one day in UTC+13 timezones

Steps to reproduce

1. Set the account timezone to Pacific/Auckland (UTC+13 in daylight saving)
2. Set a task due date of the 1st
3. Reload the page

Expected: due date stays on the 1st. Actual: due date renders as the 31st of the previous month.

Reported by 6 customers. Root cause is likely a UTC conversion on render rather than on save.