Fix App test

Change-Id: Iacaa6f5e70925b857f24554e6aba64234b1cae44

src/App.test.jsx

@@ -1,9 +1,10 @@
 import React from "react";
-import { render } from "@testing-library/react";
+import { render, screen } from "@testing-library/react";
 import App from "./App";
 
 describe("App", () => {
-  it("renders", () => {
+  it("renders", async () => {
     render(<App />);
+    await screen.findAllByText("Welcome to Synapse-admin");
   });
 });