List webhook subscriptions

curl --request POST \
  --url https://api.sand.getivy.de/api/service/webhook-subscription/list \
  --header 'Content-Type: application/json' \
  --header 'X-Ivy-Api-Key: <api-key>' \
  --data '{
  "limit": 123,
  "skip": 123
}'

{
  "items": [
    {
      "id": "<string>",
      "merchant": "<string>",
      "merchantApp": "<string>",
      "url": "<string>",
      "events": [
        "test"
      ],
      "updatedAt": "2023-11-07T05:31:56Z",
      "createdAt": "2023-11-07T05:31:56Z"
    }
  ],
  "skip": 123,
  "hasNext": true,
  "count": 123
}