List spending policy versions

{
  "data": [
    {
      "id": "string",
      "agent_id": "string",
      "version": 1,
      "document": {
        "network": "eip155:1",
        "asset": {
          "symbol": "USDC",
          "contract_address": "stringstringstringstringstringst"
        },
        "allowed_origins": [
          "string"
        ],
        "allowed_pay_to": [
          "stringstringstringstringstringst"
        ],
        "automatic_payment_threshold_atomic": "string",
        "per_payment_limit_atomic": "string",
        "agent_daily_limit_atomic": "string",
        "require_approval_for_unknown_origin": true,
        "require_approval_for_unknown_pay_to": true
      },
      "document_hash": "string",
      "created_by": "string",
      "created_at": "2019-08-24T14:15:22Z",
      "activated_at": "2019-08-24T14:15:22Z",
      "superseded_at": "2019-08-24T14:15:22Z"
    }
  ]
}