Obsolete Exception API on Windows

[jfversluis]

While working on #76 I noticed that Windows is now issuing warnings about an obsolete Exception API we're using.

Not top priority, but we probably want to get rid of it soon-ish.

D:\a\Plugin.Maui.Audio\Plugin.Maui.Audio\src\Plugin.Maui.Audio\FailedToLoadAudioException.shared.cs(18,89): warning SYSLIB0051: 'Exception.Exception(SerializationInfo, StreamingContext)' is obsolete: 'This API supports obsolete formatter-based serialization. It should not be called or extended by application code.' (https://aka.ms/dotnet-warnings/SYSLIB0051) [D:\a\Plugin.Maui.Audio\Plugin.Maui.Audio\src\Plugin.Maui.Audio\Plugin.Maui.Audio.csproj::TargetFramework=net8.0-windows10.0.19041.0]