Updating index.tsx to reflect changes between React 17 and 18.

src/index.tsx

@@ -1,11 +1,9 @@
 import React from 'react';
-import ReactDOM from 'react-dom';
 
 import App from './App';
 
-ReactDOM.render(
-  <React.StrictMode>
-    <App />
-  </React.StrictMode>,
-  document.getElementById('root')
-);
+import { createRoot } from 'react-dom/client';
+
+const container = document.getElementById('root');
+const root = createRoot(container!);
+root.render(<App />);