fix cart totalPrice

src/components/sell/cart.tsx

-import {Fragment, useContext} from 'react'
+import {Fragment, useContext, useEffect, useState} from 'react'
 
 import { Dialog, Transition } from '@headlessui/react'
 import { ArrowLeftIcon, EmojiSadIcon } from '@heroicons/react/outline';
@@ -15,6 +15,19 @@ const Cart = () => {
     return `${price.toFixed(2)} €`;
   }
 
+  let [totalPrice, setTotalPrice] = useState(0);
+
+  useEffect(() => {
+    // Update cart totalPrice
+    let totalPrice = 0;
+    cartState.cart.forEach((product) => {
+      if (product.quantity) {
+        totalPrice += product.price * product.quantity;
+      } 
+    });
+    setTotalPrice(totalPrice);
+  }, [cartState]);
+
   return (
     // S'abonne au contexte
     <Transition.Root show={cartState.showCart} as={Fragment}>
@@ -138,7 +151,7 @@ const Cart = () => {
                                   <dl className="-my-4 text-sm divide-y divide-gray-200">
                                     <div className="py-4 flex items-center justify-between">
                                       <dt className="text-gray-600">Total : </dt>
-                                      <dd className="font-medium text-gray-900">{renderPrice(0)}</dd>
+                                      <dd className="font-medium text-gray-900">{renderPrice(totalPrice)}</dd>
                                     </div>
                                   </dl>
                                 </div>