Adjust the audio session strategy for the AudioNavigator

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spokenAudio is better suited for the AudioSession mode, as it will interrupt the audiobook playback when a spoken notification is triggered.

Appropriate for applications which play spoken audio and wish to be paused (via audio session interruption) rather than ducked if another app (such as a navigation app) plays a spoken audio prompt. Examples of apps that would use this are podcast players and audio books. For more information, see the related category option AVAudioSessionCategoryOptionInterruptSpokenAudioAndMixWithOthers.