Add Audio support

[Bhasfe]

• I have been using the package for a project, and I had a case to add an audio file to generated epub. I have basically used the AddVideo functionality to implement AddAudio

[coveralls]

Coverage: 86.799% (+0.2%) from 86.638% when pulling cb555ed on Bhasfe:main into 74b49e5 on bmaupin:main.

[bmaupin]

@Bhasfe The code looks great! I only see one thing that should probably be changed; testdata/sample_audio.wav is rather large (17.8 MB). Could you please replace it with a smaller file? Ideally under 1 MB. Thanks!

[Bhasfe]

@Bhasfe The code looks great! I only see one thing that should probably be changed; testdata/sample_audio.wav is rather large (17.8 MB). Could you please replace it with a smaller file? Ideally under 1 MB. Thanks!

Thank's for your kind and fast response. I replace the audio file with a 1.1 mb wav found here:
https://file-examples.com/index.php/sample-audio-files/sample-wav-download

[bmaupin]

I went ahead and found an even smaller wav file, just to try to keep the repo size to a minimum. I squashed the commits to avoid the larger files being in the commit history and merged your changes.

It's tagged as release v1.1.0.

Thanks for your contribution!