### 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.
publish: Publish = None,
        version_description: VersionDescription = None,
    ) -> UpdateStateMachineOutput:
        state_machines = self.get_store(context).state_machines
        state_machine = state_machines.get(state_machine_arn)
        if not isinstance(state_machine, StateMachineRevision):
            raise StateMachineDoesNotExist(f"State Machine Does Not Exist: '{state_machine_arn}'")
        if not any([definition, role_arn, logging_configuration]):
            raise MissingRequiredParameter(
                "Either the definition, the role ARN, the LoggingConfiguration, or the TracingConfiguration must be specified"
            )
        if definition is not None:
            self._validate_definition(definition=definition)
        revision_id = state_machine.create_revision(definition=definition, role_arn=role_arn)
        version_arn = None
        if publish:
            version = state_machine.create_version(description=version_description)
            if version is not None:
                version_arn = version.arn
                state_machines[version_arn] = version
            else:
                target_revision_id = revision_id or state_machine.revision_id
                version_arn = state_machine.versions[target_revision_id]
        update_output = UpdateStateMachineOutput(updateDate=datetime.datetime.now())
        if revision_id is not None:
            update_output["revisionId"] = revision_id
        if version_arn is not None:
            update_output["stateMachineVersionArn"] = version_arn
        return update_output
    def publish_state_machine_version(