partition-id should be field-id in UnboundPartitionField

[FANNG1]

please refer https://github.com/apache/iceberg/blob/main/open-api/rest-catalog-open-api.yaml#L1921

  PartitionField:
      type: object
      required:
        - source-id
        - transform
        - name
      properties:
        field-id:
          type: integer
        source-id:
          type: integer
        name:
          type: string
        transform:
          $ref: '#/components/schemas/Transform'