Create a branch for Drupal 10.3.x

The 9.1.x branch causes the following PHPStan error.

Class Drupal\display_fields\Element\EntityFieldSelect extends deprecated class Drupal\Core\Render\Element\FormElement: in drupal:10.3.0 and is removed from drupal:12.0.0. use \Drupal\Core\Render\Element\FormElementBase instead.

The \Drupal\Core\Render\Element\FormElementBase class does not exist before Drupal 10.3.x. That change can be done only for a branch that is compatible with Drupal 10.3.0 or higher versions.