made group trigger keyword case insensitive

fix #140

Author: n3d1117

bot/telegram_bot.py

@@ -345,7 +345,7 @@ async def prompt(self, update: Update, context: ContextTypes.DEFAULT_TYPE):
 
         if self.is_group_chat(update):
             trigger_keyword = self.config['group_trigger_keyword']
-            if prompt.startswith(trigger_keyword):
+            if prompt.lower().startswith(trigger_keyword.lower()):
                 prompt = prompt[len(trigger_keyword):].strip()
             else:
                 if update.message.reply_to_message and update.message.reply_to_message.from_user.id == context.bot.id: