Add Credit Note Attachments

curl --request POST \
  --url https://api.sandbox.flowpayroll.ai/v1/billing/clients/{clientId}/credit-notes/{creditNoteId}/attachments \
  --header 'Content-Type: application/json' \
  --header 'X-Auth-Token: <api-key>' \
  --data '
{
  "attachments": [
    {
      "fileName": "<string>",
      "contentType": "<string>",
      "fileSize": 123
    }
  ]
}
'

{
  "content": {
    "data": [
      {
        "attachmentId": "<string>",
        "fileName": "<string>",
        "uploadUrl": "<string>",
        "expiresAt": "<string>"
      }
    ],
    "metadata": {
      "dateFormat": "<string>",
      "dateTimeFormat": "<string>"
    }
  },
  "metadata": {
    "dateFormat": "<string>",
    "dateTimeFormat": "<string>"
  },
  "errors": [
    {
      "field": "<string>",
      "reasonText": "<string>",
      "reasonId": "<string>",
      "reasonParameters": [
        {
          "key": "<string>",
          "value": "<string>"
        }
      ]
    }
  ],
  "message": {
    "text": "<string>",
    "textId": "<string>",
    "textParameters": [
      {
        "key": "<string>",
        "value": "<string>"
      }
    ]
  }
}