database: Add missing virtual destructors for some classes

database/categorydao.h

@@ -15,6 +15,7 @@ class CategoryDao
 	virtual std::optional<Category> find(std::string name) = 0;
 	virtual void deleteCategory(std::string name) = 0;
 	virtual std::vector<Page> fetchMembers(std::string name, QueryOption o) = 0;
+	virtual ~CategoryDao() = default;
 };
 
 #endif // CATEGORYDAO_H