core: Resolve C4267 warning on MSVC

src/core/file_sys/seed_db.cpp

@@ -143,7 +143,7 @@ u32 GetSeedCount() {
     if (!db.Load()) {
         return 0;
     }
-    return db.GetCount();
+    return static_cast<u32>(db.GetCount());
 }
 
 } // namespace FileSys