Permanently update Dartmoor slots
Permanently update Dartmoor slots

Dartmoor have changed some of their slot days/times.  A previous PR was
merged to cover the interim period before the change needed to come into
affect (https://github.com/ministryofjustice/prison-visits-2/pull/1824).

Following 29th September we are now able to permanently change their slot
days/times.

ministryofjustice/prison-visits-2,ministryofjustice/prison-visits-2,ministryofjustice/prison-visits-2,ministryofjustice/prison-visits-2