The common cause of this error is incorrect keys or keys with typo in the config files.
Please check the data entered in the config file for any errors.
Even i got the same error when i gave my AUTH_TOKEN value incorrectly.
The main reason behind this is incorrect values of your credential which you gave.
check if you have replaced all the values with your credentials correctly in configuration file.
I have gone through your output and clearly the error is in Telegram credentials. Here are a few things you should do:
Check if you have followed each and every step properly while making a channel on telegram.
The main issue might be with the admin rights of bot in your channel, please go to admin and enable post right for your bot.
Lastly, check if your following variables for telegram credentials are correct in conf.py file.
telegram_chat_id = "@XXXX" # This is the channel ID of the created Telegram channel. Paste after @ telegram_bot_id = "botXXXX" # This is the bot ID of the created Telegram Bot. Paste after bot
Hope this helps, cheers!