social_group_flexible_group_update_130003 fails with sub group type

Problem/Motivation

The update hook social_group_flexible_group_update_130003 fails if Socal\Group has a subclass and this sub class is set in entity type alter.

Steps to reproduce

namespace Drupal\mkat_group\Entity;

use Drupal\social_group\Entity\Group as SocialGroup;

/**
 * Bundle class for groups.
 */
class Group extends SocialGroup {
...
}

Proposed resolution

Use

\Drupal::entityTypeManager()->getStorage('group')->load($item->gid); 

Instead of

Group::load($item->gid);

in social_group_flexible_group_update_130003

There is a similar issue in drupal core:

https://www.drupal.org/project/drupal/issues/3127026