Unable to upgrade the current ansible tower version

latest version which i am using of ansible tower is:-
version:- ansible 2.5.1
And want to upgrade to :- version:- 3.2.3
I followed the up gradation steps:-
wget http://releases.ansible.com/ansible-tower/setup/
tar -xvzf ansible-tower-setup-latest.tar.gz
ls
cd ansible-tower-setup-3.2.3/
ls
here i went inside the inventory file but where to change the ansible tower
version ?
the version is missing den how to upgarde from 2.5.1 to ansible-tower 3.2.3