Add explicit include for boost/filesystem/directory.hpp

This mends the build process on distros with a boost version of 1.85
and above.

Fixes prusa3d#13795

src/slic3r/Config/Version.cpp

@@ -7,6 +7,7 @@
 #include <cctype>
 
 #include <boost/filesystem/operations.hpp>
+#include <boost/filesystem/directory.hpp>
 #include <boost/nowide/fstream.hpp>
 
 #include "libslic3r/libslic3r.h"