`transform` seem to be exported incorrectly

Node: v14.17.5

```js
const { transform } = require('unplugin-vue2-script-setup')
console.log(transform) // print undefined
```

I configure my jest followed the documentation, not work

```js
module.exports = {
  transform: {
    '.*\\.(vue)$': 'unplugin-vue2-script-setup/jest',
  },
}
```