Fix chat_kwargs() missing chat_id arg in multi-media send paths

Two call sites in send_media_post() (the >1-media-item send_media_group
branches) were missed when chat_kwargs() was parameterized for multi-route
support - broke TG posting for any post with more than one photo/video.

src/tg_poster.py

@@ -354,7 +354,7 @@ class TelegramPoster:
                 else:
                     group.append(InputMediaVideo(media=item["media"], caption=cap, parse_mode="HTML"))
             msgs = await self.tg_retry_media(
-                lambda: self.bot.send_media_group(media=group, **self.chat_kwargs())
+                lambda: self.bot.send_media_group(media=group, **self.chat_kwargs(chat_id, thread_id))
             )
             message_ids.extend(int(m.message_id) for m in msgs)
 
@@ -369,7 +369,7 @@ class TelegramPoster:
                 for item in chunk
             ]
             msgs = await self.tg_retry_media(
-                lambda: self.bot.send_media_group(media=g, **self.chat_kwargs())
+                lambda: self.bot.send_media_group(media=g, **self.chat_kwargs(chat_id, thread_id))
             )
             message_ids.extend(int(m.message_id) for m in msgs)