curl --request PUT \
  --url https://{tenant}.stamp.eu/rest/employees/{employee}/schedule_models_history \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "assignments": [
    {
      "schedule_model_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "valid_after": "2023-12-25"
    }
  ]
}
'

{
  "data": [
    {
      "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "schedule_model_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "valid_after": "2023-12-25",
      "schedule_model": {
        "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
        "name": "<string>",
        "type": 0,
        "accommodation_time": true,
        "night_begin": "<string>",
        "entries": [
          {
            "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
            "weekday": 4,
            "periods": [
              {
                "start": 123,
                "end": 123
              }
            ],
            "pauses": [
              {
                "start": 123,
                "end": 123
              }
            ],
            "core_times": [
              {
                "start": 123,
                "end": 123
              }
            ],
            "pause_thresholds": [
              {
                "threshold": 123,
                "duration": 123
              }
            ]
          }
        ],
        "created_at": "2023-11-07T05:31:56Z",
        "updated_at": "2023-11-07T05:31:56Z"
      },
      "created_at": "2023-11-07T05:31:56Z",
      "updated_at": "2023-11-07T05:31:56Z"
    }
  ]
}