cv::imwrite method signature missmatch

Following the opencv4nodejs typings, imwrite(Async) returns `void` (or `Promise`), while the actual signature is

```C++
bool imwrite(const String& filename, InputArray img, const vector& params=vector() )
```

Is there a particular reason for dropping the result of imwrite?
Or am I just missing another way to validate successful writes?

Best regards

Simon

And please keep up your great work, this package just awesome!