Add redis to CI docker image.
This enables testing of redis locks within CI.
redis install @ centos (-> gms_bas_centos.docker) https://linode.com/docs/databases/redis/install-and-configure-redis-on-centos-7/
sudo yum install epel-release # Add the EPEL repository
sudo yum update # update YUM to confirm your change
sudo yum install redis # Install Redis
sudo systemctl start redis # Start Redis
sudo systemctl enable redis # Optional: To automatically start Redis on boot