[ADD] docker-postgresql: postgresql13-ci files
This MR adds the Dockerfile and configuration file required to create a PostgreSQL 13.0 CI image.
These files are based on the configurations used by the postgresql14-ci image.
Tests:
-
Build the image. -
Create a container with that image. -
Connect to the PostgreSQL cluster inside the container.
Edited by José Ángel Fentánez