fix: fix ios video trimming not working when includeAudio true

[yujune]

Issue

when includeAudio is set to true, video will not be trimmed based on startTime and duration in iOS.

[ssandr1kka]

I was about to make PR about this. Btw I dont think the work is complete, I did that and it didnt wokr for me on IOS... I found out that there is another error.

video_compress/ios/Classes/SwiftVideoCompressPlugin.swift
lines 41-42:
let startTime = (args!["startTime"] as? NSNumber)?.doubleValue let duration = (args!["duration"] as? NSNumber)?.doubleValue
Had to make these changes too.

Probelm is that args!["startTime"] as? Double fails for NSNumber

Do not want to mess up your branch if you could append these and then this goes in, I would be very happy