Install libnginx-mod-http-passenger on newer systems

On Debian 9 & Ubuntu 18.04 libnginx-mod-http-passenger needs to be
installed instead of passenger according to the installation guide by
passenger. libnginx-mod-http-passenger has a dependency on passenger, so
it will be installed. Without libnginx-mod-http-passenger nginx will not
be able to handle passenger.

Installation guide:
https://www.phusionpassenger.com/docs/tutorials/deploy_to_production/installations/oss/ownserver/ruby/nginx/