message: remove getheapstats, not exist in 2.3.0
diff: @@ -2558,8 +2558,8 @@ void WiFiManager::DEBUG_WM(wm_debuglevel_t level,Generic text,Genericb textb) {
  uint16_t max;
  uint8_t frag;
  #ifdef ESP8266
  - ESP.getHeapStats(&free, &max, &frag);
  - _debugPort.printf("[MEM] free: %5d | max: %5d | frag: %3d%% \n", free, max, frag);
  + // ESP.getHeapStats(&free, &max, &frag);// @todo Does not exist in 2.3.0
  + // _debugPort.printf("[MEM] free: %5d | max: %5d | frag: %3d%% \n", free, max, frag);
  #elif defined ESP32
  // total_free_bytes; ///< Total free bytes in the heap. Equivalent to multi_free_heap_size().
  // total_allocated_bytes; ///< Total bytes allocated to data in the heap.
  