Fix ScdFile#GetAudio for OGG files

[RajahOmen]

Fix for #116, based on what I found to work when looking into it.

In addition to the test included in the PR, I ran the change against all .scd files in this rl2 pathlist via the following test code

    [RequiresGameInstallationFact]
    public void ScdFilesAreLoadedCorrectlyAll()
    {
        var gameData = RequiresGameInstallationFact.CreateGameData();
        var filePaths = File.ReadAllLines(@"C:\Users\USER\Documents\scdFiles.txt");
    
        Assert.All(
            filePaths.Select(p => {
                try
                {
                    return gameData.GetFile<ScdFile>(p);
                }
                catch
                {
                    return null;
                }
            }).Where(p => p is not null),
            file => {
                Assert.NotEmpty( file.Data );
                for (var i = 0; i < file.AudioDataCount; i++)
                {
                    Assert.NotNull(file.GetAudio(i));
                }
            }
        );
    }