Fix URL string for copy link.

templates.py

@@ -176,7 +176,7 @@ def copy_share_link_js(demo_type: DemoType) -> str:
             const url = new URL(window.location.href);
             url.searchParams.set('requirements', requirements);
             url.searchParams.set('code', code);
-            await navigator.clipboard.writeText(url);
+            await navigator.clipboard.writeText(url.toString());
             return [code, requirements]
         }}"""
     raise NotImplementedError(f'{demo_type} is not a supported demo type')