Remove unused is_same_domain import

Deleted the import of is_same_domain from class-announce.php as it was not used in the file.

Author: pfefferle

includes/handler/class-announce.php

@@ -14,7 +14,6 @@
 
 use function Activitypub\is_activity;
 use function Activitypub\is_activity_public;
-use function Activitypub\is_same_domain;
 use function Activitypub\object_to_uri;
 
 /**