### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

Currently, when passing `$$.Execution.StartTime` as a parameter to a SFN lambda, it is coming in in the format `HH:MM:SS.###`.

### Expected Behavior

`$$.Execution.StartTime` should be an ISO 8601 datetime string.

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

This is run in a docker compose file.

Step function definition is

```json
{
  "Comment": "Sample SFN",
  "StartAt": "SampleLambda",
  "States": {    
    "SampleLambda": {
      "Type": "Task",
      "Resource": "arn:aws:states:::lambda:invoke",
      "End": true,
      "Parameters": {
        "FunctionName": "Sample-Function",
        "Payload": {
          "data": {
            "startDateTime.$": "$$.Execution.StartTime"
          }
        }
      }
    }
  }
}
```

### Environment

```markdown
- OS: Mac OS Ventura 13.6.1
- LocalStack:
LocalStack version: 3.0.1.dev
LocalStack build date: 2023-11-20
LocalStack build git hash: 3e32b438
```


### Anything else?

Thank you so much for your hard work.
self._mutex = threading.Lock()
        self._history_event_list = list()
        self._event_id_gen = EventIdGenerator()
    def add_event(
        self,
        context: EventHistoryContext,
        hist_type_event: HistoryEventType,
        event_detail: Optional[EventDetails] = None,
        timestamp: Timestamp = None,
        update_source_event_id: bool = True,
    ) -> int:
        with self._mutex:
            event_id: int = self._event_id_gen.get()
            history_event = HistoryEvent()
            if event_detail:
                history_event.update(event_detail)
            history_event["id"] = event_id
            history_event["previousEventId"] = context.source_event_id
            history_event["type"] = hist_type_event
            history_event["timestamp"] = timestamp or datetime.datetime.now()
            self._history_event_list.append(history_event)
            context.last_published_event_id = event_id
            if update_source_event_id:
                context.source_event_id = event_id
            return event_id
    def get_event_history(self) -> HistoryEventList:
        with self._mutex:
            return copy.deepcopy(self._history_event_list)