Fix: The yum repository link has been changed

[TACY-octo]

Hello,

Feel free to correct me on how to write this PR it's my first :)

Bug :

fatal: [postgres1]: FAILED! => {"changed": false, "msg": "Failure downloading https://yum.postgresql.org/common/redhat/rhel-7-x86_64/pgdg-redhat-repo-latest.noarch.rpm, HTTP Error 404: Not Found"}

Caused by :

Reorganisation repository of Postgres : https://yum.postgresql.org/news/new-repo-rpms-released/

Solution :

Modify the URL and the value of the ansible_distribution condition in the vars / RedHat.yml file.

[kostiantyn-nemchenko]

@ctavian Merged, thank you!