### 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, state_machine_revision: StateMachineRevision, version: int, description: Optional[str]
    ):
        version_arn = f"{state_machine_revision.arn}:{version}"
        super().__init__(
            name=state_machine_revision.name,
            arn=version_arn,
            definition=state_machine_revision.definition,
            role_arn=state_machine_revision.role_arn,
            create_date=datetime.now(),
            sm_type=state_machine_revision.sm_type,
            logging_config=state_machine_revision.logging_config,
            tags=state_machine_revision.tags,
            tracing_config=state_machine_revision.tracing_config,
        )
        self.source_arn = state_machine_revision.arn
        self.revision_id = state_machine_revision.revision_id
        self.version = version
        self.description = description
    def describe(self) -> DescribeStateMachineOutput:
        describe_output: DescribeStateMachineOutput = super().describe()
        if self.description:
            describe_output["description"] = self.description
        return describe_output
    def itemise(self) -> StateMachineVersionListItem:
        return StateMachineVersionListItem(
            stateMachineVersionArn=self.arn, creationDate=self.create_date
        )