curl --request POST \
  --url 'https://api.flashcat.cloud/calendar/update?app_key=' \
  --header 'Content-Type: application/json' \
  --data '
{
  "cal_id": "<string>",
  "team_id": 123,
  "cal_name": "<string>",
  "description": "<string>",
  "timezone": "<string>",
  "workdays": [
    0
  ],
  "extra_cal_ids": [
    "<string>"
  ]
}
'

{
  "error": {
    "code": "<string>",
    "message": "<string>"
  }
}