message: Update WiFiManager.cpp
  Avoid constructing two String objects and adding them together. Just concatenate c-strings.
diff: @@ -2209,7 +2209,7 @@ String WiFiManager::getInfoData(String id){
  }
  else if(id==F("aboutdate")){
  p = FPSTR(HTTP_INFO_aboutdate);
  - p.replace(FPSTR(T_1),String(__DATE__) + " " + String(__TIME__));
  + p.replace(FPSTR(T_1),String(__DATE__ " " __TIME__));
  }
  return p;
  }
  