curl --request GET \
  --url https://external-api.kalshi.com/trade-api/v2/exchange/schedule

{
  "schedule": {
    "standard_hours": [
      {
        "start_time": "2023-11-07T05:31:56Z",
        "end_time": "2023-11-07T05:31:56Z",
        "monday": [
          {
            "open_time": "<string>",
            "close_time": "<string>"
          }
        ],
        "tuesday": [
          {
            "open_time": "<string>",
            "close_time": "<string>"
          }
        ],
        "wednesday": [
          {
            "open_time": "<string>",
            "close_time": "<string>"
          }
        ],
        "thursday": [
          {
            "open_time": "<string>",
            "close_time": "<string>"
          }
        ],
        "friday": [
          {
            "open_time": "<string>",
            "close_time": "<string>"
          }
        ],
        "saturday": [
          {
            "open_time": "<string>",
            "close_time": "<string>"
          }
        ],
        "sunday": [
          {
            "open_time": "<string>",
            "close_time": "<string>"
          }
        ]
      }
    ],
    "maintenance_windows": [
      {
        "start_datetime": "2023-11-07T05:31:56Z",
        "end_datetime": "2023-11-07T05:31:56Z"
      }
    ]
  }
}