Update policy

Example request

{
  "policy_holder": {
    "title": "MR",
    "first_name": "John",
    "middle_name": "Junior",
    "last_name": "Doe",
    "birth_date": "1990-04-25",
    "email": "jonathan.doe@mail.com",
    "spoken_language": "en-US",
    "phone": {
      "international_prefix": "+33",
      "number": "12345678"
    },
    "address": {
      "street_address": "150 Avenue de Paris",
      "postal_code": "75001",
      "city": "Paris",
      "country": "FR"
    },
    "external_holder_id": "ab8b7d8b-cdc4-46fd-bc4d-4abb3743a6d8"
  },
  "beneficiaries": [
    {
      "title": "MR",
      "first_name": "John",
      "middle_name": "Junior",
      "last_name": "Doe",
      "birth_date": "1990-04-25",
      "email": "jonathan.doe@mail.com"
    }
  ],
  "motor_coverages": {
    "insured_items": {
      "vehicles": [
        {
          "registration_number": "4234BMW",
          "brand": "Volkswagen",
          "model": "Passat SW",
          "colour": "Spatial grey"
        }
      ]
    }
  },
  "price": {
    "formula": "12-MONTHS",
    "currency": "EUR",
    "price_after_discount_inc_tax": 150.25
  },
  "quote_code": "d41d8cd98f00b204e9800998ecf8427e",
  "payment": {
    "bad_debt": {
      "amount": {
        "value": -12.75,
        "currency": "EUR"
      },
      "effective_date": "2025-08-20"
    }
  }
}