Mark destructors of several libraries as virtual.

src/Library/ItemLibrary.hpp

@@ -13,7 +13,7 @@ namespace CreatureLib::Library {
     public:
         ItemLibrary(size_t initialCapacity = 32)
             : _items(std::unordered_map<std::string, const Item*>(initialCapacity)){};
-        ~ItemLibrary() { _items.clear(); }
+        virtual ~ItemLibrary() { _items.clear(); }
 
         [[nodiscard]] const Item* GetItem(const std::string& name) const;
         [[nodiscard]] const Item* operator[](const std::string& name) const;