Fix building with new Boost 1.79.0.

Fixes #8302

src/slic3r/GUI/DesktopIntegrationDialog.cpp

@@ -10,6 +10,7 @@
 #include "libslic3r/Platform.hpp"
 #include "libslic3r/Config.hpp"
 
+#include <boost/nowide/fstream.hpp>
 #include <boost/filesystem.hpp>
 #include <boost/log/trivial.hpp>
 #include <boost/dll/runtime_symbol_info.hpp>

src/slic3r/GUI/GUI_App.cpp

@@ -13,6 +13,7 @@
 #include <cstdlib>
 #include <regex>
 #include <string_view>
+#include <boost/nowide/fstream.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/algorithm/string.hpp>
 #include <boost/format.hpp>

src/slic3r/Utils/AppUpdater.cpp

@@ -5,6 +5,7 @@
 
 #include <boost/filesystem.hpp>
 #include <boost/log/trivial.hpp>
+#include <boost/nowide/fstream.hpp>
 #include <boost/nowide/convert.hpp>
 #include <boost/property_tree/ini_parser.hpp> 
 #include <curl/curl.h>
@@ -242,7 +243,7 @@ boost::filesystem::path AppUpdater::priv::download_file(const DownloadAppData& d
 			tmp_path += format(".%1%%2%", get_current_pid(), ".download");
 			try
 			{
-				boost::filesystem::fstream file(tmp_path, std::ios::out | std::ios::binary | std::ios::trunc);
+				boost::nowide::fstream file(tmp_path, std::ios::out | std::ios::binary | std::ios::trunc);
 				file.write(body.c_str(), body.size());
 				file.close();
 				boost::filesystem::rename(tmp_path, dest_path);