List all webhook subscriptions

curl --request GET \
  --url https://api.staging.relayapp.im/v1/webhook-subscriptions \
  --header 'Authorization: Bearer <token>'

{
  "subscriptions": [
    {
      "id": "<string>",
      "target_url": "<string>",
      "subscribed_events": [
        "message.sent"
      ],
      "is_active": true,
      "created_at": "2023-11-07T05:31:56Z",
      "updated_at": "2023-11-07T05:31:56Z"
    }
  ]
}

{
  "error": {
    "status": 123,
    "code": 123,
    "message": "<string>",
    "doc_url": "<string>",
    "retry_after": 123
  },
  "success": true,
  "trace_id": "<string>"
}

{
  "error": {
    "status": 123,
    "code": 123,
    "message": "<string>",
    "doc_url": "<string>",
    "retry_after": 123
  },
  "success": true,
  "trace_id": "<string>"
}

{
  "error": {
    "status": 123,
    "code": 123,
    "message": "<string>",
    "doc_url": "<string>",
    "retry_after": 123
  },
  "success": true,
  "trace_id": "<string>"
}