curl --request GET \
  --url http://localhost:8080/promo-groups

{
  "items": [
    {
      "id": 123,
      "name": "<string>",
      "server_discount_percent": 123,
      "traffic_discount_percent": 123,
      "device_discount_percent": 123,
      "apply_discounts_to_addons": true,
      "is_default": true,
      "period_discounts": {},
      "auto_assign_total_spent_kopeks": 123,
      "members_count": 0,
      "created_at": "2023-11-07T05:31:56Z",
      "updated_at": "2023-11-07T05:31:56Z"
    }
  ],
  "total": 123,
  "limit": 123,
  "offset": 123
}