curl --request GET \
  --url https://api.elections.kalshi.com/trade-api/v2/series/fee_changes

{
  "series_fee_change_arr": [
    {
      "FeeMultiplier": 123,
      "FeeType": "<string>",
      "ID": "<string>",
      "ScheduledTs": "2023-11-07T05:31:56Z",
      "SeriesTicker": "<string>"
    }
  ]
}