Fix "Call to undefined method OCA\\WorkflowEngine\\Entity\\File::t()"

Signed-off-by: Joas Schilling <coding@schilljs.com>

apps/workflowengine/lib/Entity/File.php

@@ -172,7 +172,7 @@ class File implements IEntity, IDisplayText, IUrl {
 		}
 
 		$options = [
-			$user ? $user->getDisplayName() : $this->t('Someone'),
+			$user ? $user->getDisplayName() : $this->l10n->t('Someone'),
 			$node->getName()
 		];