Clear warning from admin-client prod build

admin-client/src/components/header.js

@@ -8,7 +8,6 @@ import {Button, IconButton} from "@mui/material";
 
 import "./header.scss";
 import {useAuth} from "../services/authentication/use-auth";
-import {Breadcrumb} from "./breadcrumb";
 
 export default function Header() {
     const navigate = useNavigate();