Update cla_common to 0.3.9
Update cla_common to 0.3.9

This version of cla_common updates some functions which impose their own
checks on availability hours rather than using the OPERATOR_HOURS object

ministryofjustice/cla_backend,ministryofjustice/cla_backend,ministryofjustice/cla_backend,ministryofjustice/cla_backend