Use dynamic import for cast/demo to show latest build (#6202)

src/html/index.html.template

@@ -52,7 +52,7 @@
     <%= renderTemplate('_js_base') %>
     <%= renderTemplate('_preload_roboto') %>
 
-    <script>
+    <script crossorigin="use-credentials">
       import("<%= latestCoreJS %>");
       import("<%= latestAppJS %>");
       window.customPanelJS = "<%= latestCustomPanelJS %>";