Retrieve a purchase order by ID

curl --request GET \
  --url https://api.zivio.net/api/v3/purchase_orders/{id} \
  --header 'X-API-Key: <api-key>' \
  --header 'zivio-tenant-id: <api-key>'

{
  "id": "23",
  "external_provider": "External Service",
  "external_id": "EX67868",
  "po_number": "EX67868",
  "version": 123,
  "status": "<string>",
  "owners": {
    "job": "2",
    "supplier": "2"
  }
}