Remove serviceworker

I was getting "Unhandled Rejection (SecurityError): The operation is insecure."
in firefox.

See badges/shields#3901

frontend/src/index.tsx

@@ -6,7 +6,6 @@ import store from "./store";
 import "./index.css";
 
 //import App from "./app/App";
-import * as serviceWorker from "./serviceWorker";
 
 // From https://redux-toolkit.js.org/tutorials/advanced-tutorial
 const render = () => {
@@ -32,8 +31,3 @@ if (process.env.NODE_ENV === "development" && module.hot) {
 // Concurrent Mode
 // @ts-ignore
 //ReactDOM.createRoot(document.getElementById("root")).render(<App />);
-
-// If you want your app to work offline and load faster, you can change
-// unregister() to register() below. Note this comes with some pitfalls.
-// Learn more about service workers: https://bit.ly/CRA-PWA
-serviceWorker.unregister();