xenial:
  base_image: buildpack-deps:xenial-scm
  extra_packages: virtualenv postgresql-9.5 python-dev

bionic:
  base_image: buildpack-deps:bionic-scm
  extra_packages: postgresql-10 python-dev

focal:
  base_image: buildpack-deps:focal-scm
  extra_packages: postgresql-12 python2-dev