curl --request GET \
  --url https://api.contextual.ai/v1/billing/balance/top-ups \
  --header 'Authorization: Bearer <token>'

{
  "top_ups": [
    {
      "amount": 123,
      "created_at": "2023-11-07T05:31:56Z",
      "description": "<string>",
      "starting_balance": 123,
      "ending_balance": 123
    }
  ],
  "has_more": true,
  "cursor": "<string>"
}