Fix SinglyLinkedList test and add to ligma.config

ligma.config.js

@@ -6,6 +6,7 @@ module.exports = {
         "BinarySearchList",
         "TwoCrystalBalls",
         "BubbleSort",
+        "SinglyLinkedList",
         "DoublyLinkedList",
         "Queue",
         "Stack",

src/__tests__/SinglyLinkedList.ts

@@ -1,7 +1,7 @@
-import LinkedList from "@code/SingleLinkedList";
+import SinglyLinkedList from "@code/SinglyLinkedList";
 import { test_list } from "./ListTest";
 
 test("linked-list", function () {
-    const list = new LinkedList<number>(3);
+    const list = new SinglyLinkedList<number>();
     test_list(list);
 });