Replace PostUpdate key-value config entries with key-value pair entries

src/Model/Contact.php

@@ -624,7 +624,7 @@ class Contact
 	public static function getPublicAndUserContactID(int $cid, int $uid): array
 	{
 		// We have to use the legacy function as long as the post update hasn't finished
-		if (DI::config()->get('system', 'post_update_version') < 1427) {
+		if (DI::keyValue()->get('post_update_version') < 1427) {
 			return self::legacyGetPublicAndUserContactID($cid, $uid);
 		}