add messages to message_cache for every on_message

app.py

@@ -42,6 +42,7 @@ async def on_message(message):
     try:  
         global number_of_messages
         if message.author != bot.user:
+            message_cache[message.id] = message
             lunarflu = bot.get_user(811235357663297546) #811235357663297546
             cakiki = bot.get_user(416019758492680203)