curl --request POST \
  --url https://api.kit.com/v4/tags \
  --header 'Content-Type: application/json' \
  --header 'X-Kit-Api-Key: <api-key>' \
  --data '
{
  "name": "Completed"
}
'

{
  "tag": {
    "id": 18,
    "name": "Completed",
    "created_at": "2023-02-17T11:43:55Z"
  }
}