[FIX] Ubuntu 18.04: Use the archive apt postgres repository
requested to merge vauxoo-dev/docker-ubuntu-base:18.04-use_postgres_archives_apt_repo-angelfentanez into 18.04
Related issue:
This change is required because it seems that Ubuntu 18.04 Bionic is no longer supported by the official PostgreSQL repo:
But it can be found in the archives:
Edited by José Ángel Fentánez