MimeType 'audio/wav' since no more supported by Safari Preview 117

[oanguenot]

When testing the polyfill in Safari 14.01:
MediaRecorder.isTypeSupported('audio/wav') --> true
MediaRecorder.isTypeSupported('audio/mp4') --> false

When testing the polyfill in Safari 14.1 (SAfari preview 117):
MediaRecorder.isTypeSupported('audio/wav') --> false
MediaRecorder.isTypeSupported('audio/mp4') --> true

[ai]

PR is welcome since I do not use this tool anymore

[jamsch]

It seems as though Safari 14.0.3 now has MediaRecorder API support with audio/mp4 support, but not audio/wav. Still using this library to polyfill override the default MediaRecorder on Safari because it seems like there's issues with the event fire order of stop & dataavailable that prevents us from getting the last chunk of data.