`get_work_orders` bounded a BETWEEN on the datetime columns `creation`
and `actual_end_date` with a bare date `to_date`, which MariaDB coerces
to midnight. Work orders created after 00:00:00 on the period's last day
were therefore dropped from the report (and made the new coverage test
fail on month-end CI runs). Extend `to_date` to end of day.