Always update slider dimensions on resize

[BJJLangedijk]

I have an issue where a single slider item is not resizing when the browser window is resized. This is because in the [onResize] function, it checks whether the amount of slides has changed. Since this is still 1, it does nothing.

I think the only thing that needs to be done, is update the dimensions of the slider. For me it does solve the issue.

Bug reproduction scenario:

• Add carousel with 1 slidesToShow (or don't pass anything since I believe that's the default
• Open page
• Change browser window size
• Observe

Expected behaviour: The slide item should resize according to the size of the window.

Actual behaviour: The slide item remains the same size and is only updated after a refresh of the page.

[israelroldan]

OMG I had this exact issue and I was going crazy trying to figure it out 👍 Thanks for this PR!!!

[katafrakt]

+1 for this change

[rob-c-baker]

+1 This seems to work. At the very least it improves the situation.