curl --request POST \
  --url 'https://api.flashcat.cloud/calendar/update?app_key=' \
  --header 'Content-Type: application/json' \
  --data '
{
  "cal_id": "cal.QiNvtdKs4Wj52kZhT3LafM",
  "cal_name": "Production On-Call Calendar (Updated)",
  "timezone": "America/New_York",
  "workdays": [
    1,
    2,
    3,
    4,
    5
  ]
}
'

{
  "request_id": "01HK8XQE3Z7JM2NTFQ5YJ8P9R4",
  "data": {}
}