Fix storing token in ClientStub when config hash is given

lib/telegram/bot/client_stub.rb

@@ -35,7 +35,7 @@ module Telegram
       end
 
       def initialize(token = nil, username = nil, **options)
-        @token = token
+        @token = token || options[:token]
         @username = username || options[:username] || token
         reset
       end