Add support for showing the native OS incoming call screen when starting new Element Calls

ElementX/SupportingFiles/target.yml

@@ -90,8 +90,9 @@ targets:
         NSLocationWhenInUseUsageDescription: Grant location access so that $(APP_DISPLAY_NAME) can share your location.
         NSFaceIDUsageDescription: Face ID is used to access your app.
         UIBackgroundModes: [
-          fetch,
           audio,
+          fetch,
+          processing,
           voip
         ]
         BGTaskSchedulerPermittedIdentifiers: [