fix: fix es6 import file extension

tests/api.test.js

@@ -1,10 +1,10 @@
 import { jest } from "@jest/globals";
 import axios from "axios";
 import MockAdapter from "axios-mock-adapter";
-import api from "../api/index";
-import calculateRank from "../src/calculateRank";
-import renderStatsCard from "../src/cards/stats-card";
-import { CONSTANTS, renderError } from "../src/common/utils";
+import api from "../api/index.js";
+import calculateRank from "../src/calculateRank.js";
+import renderStatsCard from "../src/cards/stats-card.js";
+import { CONSTANTS, renderError } from "../src/common/utils.js";
 
 const stats = {
   name: "Anurag Hazra",