Update Header component to use localStorage for username

frontend/src/Components/Header.tsx

@@ -1,7 +1,7 @@
 import { useState } from "react";
 import { Link } from "react-router-dom";
 
-function Header({ username }: { username: string }): JSX.Element {
+function Header(): JSX.Element {
   const [isOpen, setIsOpen] = useState(false);
 
   const handleLogout = (): void => {
@@ -31,7 +31,7 @@ function Header({ username }: { username: string }): JSX.Element {
         }}
       >
         <button className="mr-4 underline font-bold text-white">
-          {username}
+          {localStorage.getItem("username")}
         </button>
 
         {isOpen && (