Create a webhook subscription

curl --request POST \
  --url https://api.sand.getivy.de/api/service/webhook-subscription/create \
  --header 'Content-Type: application/json' \
  --header 'X-Ivy-Api-Key: <api-key>' \
  --data '{
  "url": "<string>",
  "events": [
    "test"
  ]
}'

{
  "id": "<string>",
  "merchant": "<string>",
  "merchantApp": "<string>",
  "url": "<string>",
  "events": [
    "test"
  ],
  "updatedAt": "2023-11-07T05:31:56Z",
  "createdAt": "2023-11-07T05:31:56Z"
}