Update HMP Durham adult age
Update HMP Durham adult age

Following the recent changes to HMP Durham's 'adult age' to anyone over
the age of 2, they have come back and asked us to increase this to
anyone over 10.  This PR does this very change!§

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