remove unimplemented method

Author: evgeny-pol

Assets/AppCenter/Plugins/AppCenterSDK/Crashes/iOS/CrashesInternal.cs

@@ -108,9 +108,6 @@ public static ErrorReport LastSessionCrashReport()
         [DllImport("__Internal")]
         private static extern IntPtr appcenter_unity_crashes_last_session_crash_report();
 
-        [DllImport("__Internal")]
-        private static extern void appcenter_unity_crashes_set_user_confirmation_handler(IntPtr handler);
-
         [DllImport("__Internal")]
         private static extern string app_center_unity_crashes_error_report_exception_name(IntPtr errorReport);