fix(telegram): import Set for _dm_topic_chat_ids annotation

self._dm_topic_chat_ids: Set[str] = {...} at line 460 references Set
but only Dict, List, Optional, Any are imported from typing. The file
has no 'from __future__ import annotations', so the annotation is
evaluated at runtime and raises NameError on TelegramAdapter
construction.

gateway/platforms/telegram.py

@@ -16,7 +16,7 @@ import tempfile
 import html as _html
 import re
 from datetime import datetime, timezone
-from typing import Dict, List, Optional, Any
+from typing import Dict, List, Optional, Set, Any
 
 logger = logging.getLogger(__name__)