Preserve Alpine.js @click syntax

I use [Alpine.js](https://alpinejs.dev) in my HTML and event could be short written with like this:

```html
<button @click="open = true">Expand</button>
```

If I open a document with `HTMLDocument`, the output removes the `@click` attribute:

```html
<button>Expand</button>
```

Any idea how I can preserve the `@click` attribute? 