Fix typo

Arbitrary-callback_data.md

@@ -34,7 +34,7 @@ Callback updates are not sent by Telegram, but by the client. This means that th
 
 Most of the time, this is not really a problem, since `callback_data` often just is `Yes`, `No`, etc. However, if the callback data is something like `delete message_id 123`, the malicious user could delete any message sent by the bot.
 
-When using `arbitrary_callback_data` as described above, PTB replaces the outgoing `callback_data` with a [UUID](https://docs.python.org/3/library/uuid.html), i.e., a random unique identifier. This makes the `callback_data` safe: If a malicious client alters the scent `CallbackQuery`, the invalid UUID can't be resolved. In this case `CallbackQuery.data` will be an instance of `telegram.ext.InvalidCallbackData`. Note that this is also the case, when the UUID *was* valid, but the data has already been dropped from cache - PTB can't distinguish between the two cases.
+When using `arbitrary_callback_data` as described above, PTB replaces the outgoing `callback_data` with a [UUID](https://docs.python.org/3/library/uuid.html), i.e., a random unique identifier. This makes the `callback_data` safe: If a malicious client alters the sent `CallbackQuery`, the invalid UUID can't be resolved. In this case `CallbackQuery.data` will be an instance of `telegram.ext.InvalidCallbackData`. Note that this is also the case, when the UUID *was* valid, but the data has already been dropped from cache - PTB can't distinguish between the two cases.
 
 ## Manually handling updates