fix: refactor Book constructor to use class syntax

Author: jakr-s

debugging/book-library/script.js

@@ -36,11 +36,13 @@ function submit() {
   render();
 }
 
-function Book(title, author, pages, check) {
-  this.title = title;
-  this.author = author;
-  this.pages = pages;
-  this.check = check;
+class Book {
+  constructor(title, author, pages, check) {
+    this.title = title;
+    this.author = author;
+    this.pages = pages;
+    this.check = check;
+  }
 }
 
 function render() {