fix: Made changes to prevent breaking

[viren-joshi]

I was facing issue with the library and the error

ERROR: 'RenderCircleListViewport.getOffsetToReveal' ('RevealedOffset Function(RenderObject, double, {Rect? rect})') isn't a valid override of 'RenderAbstractViewport.getOffsetToReveal' ('RevealedOffset Function(RenderObject, double, {Axis? axis, Rect? rect})').

This was the same error pointed out by pub.dev's static analysis.

So this simple change fixes the error and also increases the code score of the package on pub.dev.