fix: code style error

Author: BekzodIsakov

Data-Structures/Linked-List/test/SinglyLinkedList.test.js

@@ -148,7 +148,7 @@ describe('SinglyLinkedList', () => {
 
     list.addFirst(30)
     expect(list.head()).toBe(30)
-    
+
     // check for a falsy head data
     list.addFirst(false)
     expect(list.head()).toBe(false)