Fix compilation with boost 1.74.0

The serialization module was heavily changed and it now this header needs to be included as it is relied in many other parts of citra.

src/core/frontend/applets/mii_selector.h

@@ -6,6 +6,7 @@
 
 #include <memory>
 #include <string>
+#include <boost/serialization/version.hpp>
 #include "core/hle/applets/mii_selector.h"
 
 namespace Frontend {