net/ftp.rb: kwargs

* lib/net/ftp.rb (Net::FTP#open_socket): use keyword argument.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56780 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/net/ftp.rb

@@ -242,9 +242,7 @@ module Net
         else
           sock = TCPSocket.open(host, port)
         end
-        io = BufferedSocket.new(sock)
-        io.read_timeout = @read_timeout
-        io
+        BufferedSocket.new(sock, read_timeout: @read_timeout)
       }
     end
     private :open_socket