Global import broken
### 🐛 The bug

With the previous version `phosphor-vue`, global import was possible using

```ts
import { createApp } from 'vue'
import PhosphorVue from 'phosphor-vue'

const app = createApp(App)
app
  .use(PhosphorVue)

app.mount('#app')
```

With the new version, this is not possible anymore.

### 🛠️ To reproduce

https://stackblitz.com/edit/vue-dniokx?file=src/main.js

### 🌈 Expected behaviour

that switching to the new package works straightforward (just like written in the README.md)

### ℹ️ Additional context

_No response_