Fix subscribe() -> add_moderator() in sync_moderators()

mailman_sync.py

@@ -112,7 +112,7 @@ def sync_moderators(
     for address, display_name in members_to_add.items():
         print(f"Adding '{display_name} <{address}>' as moderator to list {list}")
         if not dry_run:
-            list.subscribe(address, display_name)
+            list.add_moderator(address, display_name)
 
     for member in members_to_remove:
         print(f"Removing {member} as moderator from list {list}")