small fix

Fixed "ERROR - TeleBot: "message_handler: Commands filter should be list of strings (commands), unknown type supplied to the 'commands' filter list. Not able to use the supplied type."

examples/custom_states.py

@@ -47,7 +47,7 @@ def start_ex(message):
 
 
 # Any state
-@bot.message_handler(state="*", commands='cancel')
+@bot.message_handler(state="*", commands=['cancel'])
 def any_state(message):
     """
     Cancel state