type attribute on included scripts is not preserved

### Expected behaviour

`type` attribute on included scripts should be preserved when client.runInParent is true and client.useIframe is false.

### Actual behaviour

The type attribute is removed.

### Environment Details

- Karma version (output of `karma --version`): 2.0.0
- Relevant part of your `karma.config.js` file: files property

### Steps to reproduce the behaviour

1. Create a basic Karma config
2. Include a file with the following options:
```
{
pattern: './file-to-include.js',
included: true,
served: true,
watched: true,
type: 'module'
}
```
3. Set client.runInParent to true and client.useIframe to false
4. Run Karma, inspect the scripts for the type attribute