Get optimal positions for portfolio

curl --request GET \
  --url https://sandbox.axle.energy/entities/portfolio/{geography_id}/optimal

{
  "timestamps": [
    "2023-11-07T05:31:56Z"
  ],
  "demand": [
    123
  ],
  "delta_to_median": [
    123
  ],
  "value_of_delta_eur": [
    123
  ],
  "market": [
    "day_ahead"
  ]
}