fix src/PluginRTCAudioOutputController.swift deprecated error
fix src/PluginRTCAudioOutputController.swift deprecated error

hit0907/cordova-plugin-iosrtc,BasqueVoIPMafia/cordova-plugin-iosrtc,eface2face/cordova-plugin-iosrtc,BasqueVoIPMafia/cordova-plugin-iosrtc,BasqueVoIPMafia/cordova-plugin-iosrtc,hit0907/cordova-plugin-iosrtc,eface2face/cordova-plugin-iosrtc,eface2face/cordova-plugin-iosrtc,hit0907/cordova-plugin-iosrtc