Use of the Drupal 11+ method EntityInterface::getOriginal tiggers error on Drupal 10

Problem/Motivation

on Drupal 10 saving content could trigger the following error:

Error: Call to undefined method Drupal\redirect_regex\Entity Redirect\Regex::getOriginal() in Drupal\Redirect_regex\Entity\RedirectRegex->postSave() (line 19 of modules/contrib/redirect_regex/src/Entity/RedirectRegex.php).
\Core\Entity\EntityStorageBase->doPostSave) (Line: 781)
\Core\Entity\ContentEntityStorageBase->doPostSave() (Line: 489)
\Core\Entity\EntityStorageBase->save()(Line:806)
\Core\Entity\Sql\SqlContentEntityStorage>save) (Line: 354)
\Core\Entity\EntityBase->save) (Line: 107)
redirect_path_alias_update()
call_user_func_array) (Line: 416)
Drupal\Core\Extension\ModuleHandler->Drupal\Core\Extension\tclosurer) (Line: 395)
Drupal\Core\Extension\ModuleHandler->invokeAllWith) (Line: 415)
Drupal\Core\Extension\ModuleHandler->invokeAll) (Line: 215)
Drupal\Core\Entity\EntityStorageBase->invokeHook() (Line: 900)
Drupal\Core\Entity\ContentEntityStorageBase->invokeHook) (Line: 564)
Drupal\Core\Entity\EntityStorageBase->doPostSave() (Line: 781)
Drupal\Core\Entity\ContentEntityStorageBase->doPostSave() (Line: 489)
Drupal\Core\Entity\EntityStorageBase->save() (Line: 806)

The EntityInterface::getOriginal method is only available to Drupal 11+ but the module require ">=10".

Code used :

    if ($this->isRedirectRegex() || $this->isRedirectRegexEntity($this->getOriginal())) {

See https://www.drupal.org/node/3571065

Rewrites the deprecated $entity->original magic property, removed in drupal:12.0.0 (deprecated drupal:11.2.0, issue #3571065). Read accesses become $entity->getOriginal() and write assignments become $entity->setOriginal($value). Skips $this->original to avoid false positives on non-entity classes such as EntityTypeEvent and FieldStorageDefinitionEvent that have a legitimate $original property.
core_version_requirement: '>=10'

Proposed resolution

Create a version for D10, using $entity->original