Migrate away from deprecated `std::iterator` class

src/base/utils/io.h

@@ -40,9 +40,15 @@ namespace Utils
     {
         // A wrapper class that satisfy LegacyOutputIterator requirement
         class FileDeviceOutputIterator
-            : public std::iterator<std::output_iterator_tag, void, void, void, void>
         {
         public:
+            // std::iterator_traits
+            using iterator_category = std::output_iterator_tag;
+            using difference_type = void;
+            using value_type = void;
+            using pointer = void;
+            using reference = void;
+
             explicit FileDeviceOutputIterator(QFileDevice &device, const int bufferSize = (4 * 1024));
             FileDeviceOutputIterator(const FileDeviceOutputIterator &other) = default;
             ~FileDeviceOutputIterator();