addLogWithSeverity method isn't compatible with the interface.

Problem/Motivation

Since the latest release, I'm getting these errors, completely breaking my site:

PHP Fatal error:  Declaration of Drupal\entity_logger\EntityLoggerInstance::addLogWithSeverity(string $message, array $context = Array, int $severity = Drupal\Core\Logger\RfcLogLevel::INFO) must be compatible with Drupal\entity_logger\EntityLoggerInstanceInterface::addLogWithSeverity(string $message, array $context = Array, int $severity = Drupal\Core\Logger\RfcLogLevel::INFO): ?Drupal\entity_logger\Entity\EntityLogEntryInterface in /var/web/vd20442/livalos-project-builder/develop/web/modules/contrib/entity_logger/src/EntityLoggerInstance.php on line 63
PHP Fatal error:  Uncaught Error: Call to a member function setDisplayConfigurable() on null in /var/web/vd20442/livalos-project-builder/develop/web/modules/contrib/entity_logger/src/Entity/EntityLogEntry.php:177
Stack trace:
#0 /var/web/vd20442/livalos-project-builder/develop/web/core/lib/Drupal/Core/Entity/EntityFieldManager.php(228): Drupal\entity_logger\Entity\EntityLogEntry::baseFieldDefinitions(Object(Drupal\Core\Entity\ContentEntityType))
#1 /var/web/vd20442/livalos-project-builder/develop/web/core/lib/Drupal/Core/Entity/EntityFieldManager.php(193): Drupal\Core\Entity\EntityFieldManager->buildBaseFieldDefinitions('entity_log_entr...')
#2 /var/web/vd20442/livalos-project-builder/develop/web/core/lib/Drupal/Core/Entity/EntityFieldManager.php(448): Drupal\Core\Entity\EntityFieldManager->getBaseFieldDefinitions('entity_log_entr...')
#3 /var/web/vd20442/livalos-project-builder/develop/web/core/lib/Drupal/Core/Entity/Routing/DefaultHtmlRouteProvider.php(354): Drupal\Core\Entity\EntityFieldManager->getFieldStorageDefinitions(' in /var/web/vd20442/livalos-project-builder/develop/web/modules/contrib/entity_logger/src/Entity/EntityLogEntry.php on line 177

Steps to reproduce

Update to the latest version.

Proposed resolution

I'll attach a patch for this.

Remaining tasks

Apply patch, create new minor version.