Fix slight error in FPS calculation

[EmeraldBlock]

Currently, FPS is calculated as the number of frames (this.accumulatedFps) divided by the constant fpsAccumulationTime. However, fpsAccumulationTime is only the minimum time needed to pass, and timeDuration represents the actual amount of time that passed.

This PR changes the FPS division to use timeDuration instead of fpsAccumulationTime.

[WaffleDevs]

[email protected] made a mod for it