Fix anywidget deprecation warning (#3364)

altair/jupyter/js/index.js

@@ -6,7 +6,7 @@ import lodashDebounce from "https://esm.sh/[email protected]/debounce";
 // the javascript_bundle function for details on the available imports and their names.
 // If an additional import is required in the future, it will need to be added to vl-convert
 // in order to preserve offline support.
-export async function render({ model, el }) {
+async function render({ model, el }) {
     let finalize;
 
     function showError(error){
@@ -225,4 +225,6 @@ function trap(view, fn) {
             view.error(error);
         }
     };
-}
+}
+
+export default { render }