### 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.
hist_type_event=self.state_entered_event_type,
            event_detail=EventDetails(
                stateEnteredEventDetails=self._get_state_entered_event_details(env=env)
            ),
        )
        env.context_object_manager.context_object["State"] = State(
            EnteredTime=datetime.datetime.now().isoformat(), Name=self.name
        )
        
        if self.input_path:
            self.input_path.eval(env)
        
        self._eval_state(env)
        #
        if not isinstance(env.program_state(), ProgramRunning):
            return
        
        if self.output_path:
            self.output_path.eval(env)
        if self.state_exited_event_type is not None:
            env.event_history.add_event(
                context=env.event_history_context,
                hist_type_event=self.state_exited_event_type,
                event_detail=EventDetails(
                    stateExitedEventDetails=self._get_state_exited_event_details(env=env),
                ),
            )
        
        self._set_next(env)