DateTime filtering in transactions API

[mimol91]

It seems that list transations https://docs.formance.com/api-reference/endpoints/ledger/transactions/list-transactions-from-a-ledger API incorrectly handles non UTC times

For example query

{
  "$and": [
    {
      "$lt": {
        "timestamp": "2026-05-21T15:09:13+04:00"
      }
    }
  ]
}

Should be interpreted the same as

{
  "$and": [
    {
      "$lt": {
        "timestamp": "2026-05-21T11:09:13Z"
      }
    }
  ]
}

However the API returns different results. It seems that the timezone information is skipped and 1st query is interpreted as "2026-05-21T15:09:13Z"