Adds iOS 12 Animation Class availability handling

[lucasromanomr]

Summary

From Xcode 16 beta 1 an error appears that the CAMediaTimingFunctionName animation is not available for versions below iOS 12, so a treatment was added for it to make it work with iOS 12

https://developer.apple.com/documentation/quartzcore/camediatimingfunctionname

issue: https://github.com/Juanpe/SkeletonView/issues/572

for versions below, animation was done using controlPoints

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