Add shipments reference on invoice
Following discuss: https://discuss.tryton.org/t/add-shipment-reference-on-invoice/340
This instance will be upgraded to Heptapod 1.3.1 (GitLab 16.9.3) on 2023-03-28 at 17:00 UTC+1
Following discuss: https://discuss.tryton.org/t/add-shipment-reference-on-invoice/340