live: work around tomlkit issue

>>> from tomlkit.toml_file import TOMLFile
>>> from furcastbot.config import Config
>>> config = Config.get_config()
>>> config.config["announce"]["fc"]
['xbn', 'furcast']
>>> config.config["announce"]["fc"][1:]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "site-packages/tomlkit/items.py", line 1331, in __getitem__
    if rv.is_boolean():
       ^^^^^^^^^^^^^
AttributeError: 'list' object has no attribute 'is_boolean'

furcastbot/live.py

@@ -78,7 +78,7 @@ def post_pin(
         sent_messages = {announce_list[0]: root_message}
 
         if forward:
-            for target_chat_id in announce_list[1:]:
+            for target_chat_id in list(announce_list)[1:]:
                 sent_messages[target_chat_id] = bot.forward_message(
                     target_chat_id,
                     root_message.chat_id,