Compatibility with Composer 2

This plugin is currently not compatible with Composer 2:
```
The "drupal/console-extend-plugin" plugin was skipped because it requires a Plugin API version ("^1.0") that does not match your Composer installation ("2.0.0").
```

Here is what needs to be changed: https://github.com/composer/composer/blob/2.0.0-alpha1/UPGRADE-2.0.md#for-integrators-and-plugin-authors