fix event type in index.html (fixes #2192)

nicegui/templates/index.html

@@ -162,7 +162,7 @@
             };
             const emitter = () => window.socket?.emit("event", data);
             throttle(emitter, event.throttle, event.leading_events, event.trailing_events, event.listener_id);
-            if (element.props["loopback"] === False && event.type == "update:model-value") {
+            if (element.props["loopback"] === False && event.type == "update:modelValue") {
               element.props["model-value"] = args;
             }
           };