Fix: get audioBitrate instead of audioRate

[xage93]

This PR ensures we get audio bitrate instead of audio rate in output_getters file. Fixes the same issue as the one fixed here for output_setters.

Test Proof

Code being tested:

package main

import (
	"fmt"
	"os"

	fluentffmpeg "github.com/modfy/fluent-ffmpeg"
)

func main() {
	Cmd := fluentffmpeg.NewCommand("").
		Options("-hide_banner").
		InputPath("./audio (1)_input.wav").
		OutputFormat("mp3").
		OutputLogs(os.Stdout).
		OutputPath("./audio.mp3").
		AudioBitRate(64000).
		AudioRate(22000)

	bitRate := Cmd.Args.GetAudioBitrate()
	sampleRate := Cmd.Args.GetAudioRate()
	fmt.Println(bitRate)
	fmt.Println(sampleRate)
}

Screenshots of the code to test and the output. Basically set the output bitrate and sample rate to 64000 and 22000 respectively.

Then fetched the same and printed out. Shows the correct settings.

Before Changes - (using current release v0.1.0)

You can see that it's only setting the audioRate and then getting audioRate as well because both setter and getter use audioRate instead of audioBitrate.

After Changes

While I fixed the setter in the other PR (#13), this PR fixes the getter as well.

[xage93]

bump @CryogenicPlanet could you please merge this PR as well that fixes the issue in output_getters file.
And also would love it if a release could be done with the changes so I can use the fixed version in my code. Thanks 🙏

[xage93]

@CryogenicPlanet I've added a screenshot as test proof on your suggestion in the PR description. I've run the exact scenario I want to run in my own code which is to set the output bitrate and sample rate.
You can see that the bitrate and sample rate both are set as intended after the code change.

[CryogenicPlanet]

LGTM