Events do not occur when linking images to iOS.

When marking up img tag with anchor link, hyperlink event is canceled only on iOS, is this in the specifications?

```
// Example

```

The following if statement is seemed to be the cause of the problem.

https://github.com/akiran/react-slick/blob/90bc26c52ca8cb879f26214b9a9a9cd6621b10d7/src/utils/innerSliderUtils.js#L307

In the current situation, not only image links but also onClick events can not be used, so we want at least a click event to be allowed.