DatetimeExpression causes trailing input error

When using the new reranking functionality in query_points with a formula that includes a DatetimeExpression the following error is raised:

raise _create_rpc_error(
grpc.aio._call.AioRpcError: <AioRpcError of RPC that terminated with:
        status = StatusCode.INVALID_ARGUMENT
        details = "Wrong input: InvalidArgument: status: InvalidArgument, message: "failed to parse formula: Service internal error: trailing input", details: [], metadata: MetadataMap { headers: {"content-type": "application/grpc", "date": "Mon, 05 May 2025 05:31:47 GMT", "content-length": "0"} }"
        debug_error_string = "UNKNOWN:Error received from peer  {grpc_message:"Wrong input: InvalidArgument: status: InvalidArgument, message: \"failed to parse formula: Service internal error: trailing input\", details: [], metadata: MetadataMap { headers: {\"content-type\": \"application/grpc\", \"date\": \"Mon, 05 May 2025 05:31:47 GMT\", \"content-length\": \"0\"} }", grpc_status:3, created_time:"2025-05-05T07:31:48.460456036+02:00"}"

Formula used:

reranking_query = models.FormulaQuery(
            formula=models.SumExpression(
                sum=[
                    "$score",
                    models.DatetimeExpression(datetime='2025-05-05T07:18:25.401383')
                ]
            )
        )

Code works when replaced by:

reranking_query = models.FormulaQuery(
            formula=models.SumExpression(
                sum=[
                    "$score",
                    datetime.now().timestamp()
                ]
            )
        )

Code did not fail when tested with QdrantClient(":memory:"), only fails with the server mode.

Start at the Python client’s query_points reranking path, focusing on FormulaQuery, SumExpression, and DatetimeExpression serialization. Reproduce the reported formula against server mode and compare it with the numeric timestamp and in-memory cases. Done means a server accepts the datetime formula without the trailing-input error.