fix argument of type 'float' is not iterable (#211)

* fix argument of type 'float' is not iterable

fix "argument of type 'float' is not iterable" in show_balance_handle and message_handle

* Update bot.py

bot/bot.py

@@ -94,7 +94,7 @@ async def register_user_if_not_exists(update: Update, context: CallbackContext,
 
     # back compatibility for n_used_tokens field
     n_used_tokens = db.get_user_attribute(user.id, "n_used_tokens")
-    if isinstance(n_used_tokens, int):  # old format
+    if isinstance(n_used_tokens, int) or isinstance(n_used_tokens, float):  # old format
         new_n_used_tokens = {
             "gpt-3.5-turbo": {
                 "n_input_tokens": 0,
@@ -705,4 +705,4 @@ def run_bot() -> None:
 
 
 if __name__ == "__main__":
-    run_bot()
+    run_bot()