Use Accelerate framework on post-processing

[tucan9389]

Editing Point

https://github.com/tucan9389/PoseEstimation-https://github.com/tucan9389/PoseEstimation-TFLiteSwift/blob/da2931e39eea3065d72d4c83383387bbef482bc0/PoseEstimation-TFLiteSwift/Argmax.swift#L25-L41

Reference

https://github.com/hollance/CoreMLHelpers/blob/0bd7f983c3e73abcffb692b4428e889ed4cf01b6/CoreMLHelpers/Math.swift#L23-L82