Fix: Restart was triggered before all website data was sent

This led to the effect that e.g. the confirmation messages where  not shown.

It is somehow related to ESPAsyncWebServer 3.3.0

include/Utils.h

@@ -9,7 +9,6 @@ public:
     static uint32_t getChipId();
     static uint64_t generateDtuSerial();
     static int getTimezoneOffset();
-    static void restartDtu();
     static bool checkJsonAlloc(const JsonDocument& doc, const char* function, const uint16_t line);
     static void removeAllFiles();
 };