Add missing includes for boost::filesystem::load_string_file

Deprecated in Boost 1.79.0 and no longer included by
filesystem.hpp.

src/slic3r/Utils/PresetUpdater.cpp

@@ -9,6 +9,7 @@
 #include <boost/format.hpp>
 #include <boost/algorithm/string.hpp>
 #include <boost/filesystem.hpp>
+#include <boost/filesystem/string_file.hpp>
 #include <boost/filesystem/fstream.hpp>
 #include <boost/lexical_cast.hpp>
 #include <boost/log/trivial.hpp>