How to tint a APNG Image? 

I would like to tint a Image like

```
let imageView = UIImageView()
imageView.image = UIImage(named: "custom-icon")?.withRenderingMode(.alwaysTemplate)
imageView.tintColor = .red
```

How can I do that with APNG?

```
let imageView = APNGImageView()
imageView.image = APNGImage(named: "custom-apng-icon", progressive: true)
imageView.tintColor = .red
```

..but it does not work
