Remove no longer needed open checkout hook

lib/bigcommerce/cart/use-open-checkout.tsx

@@ -1,11 +0,0 @@
-import useCart from './use-cart'
-
-export default function useOpenCheckout() {
-  const { data, mutate } = useCart()
-
-  return async function openCheckout() {
-    window.open(data?.redirect_urls.checkout_url)
-    // Get new redirect urls
-    await mutate()
-  }
-}