add test for url extension func

src/utility/getUrlExtension.test.ts

+import { describe, test, expect } from "vitest";
+import getUrlExtension from "./getUrlExtension";
+
+describe("getUrlExtension", () => {
+	test("should return the extension of a url", () => {
+		expect(getUrlExtension("https://example.com/file.mp3")).toBe("mp3");
+	});
+
+	test("should return the extension of a url with params", () => {
+		expect(getUrlExtension("https://example.com/file.mp3?key=value&key2=.mpegvalue")).toBe("mp3");
+	});
+});