PostgreSQL 13/14 much slower than 12 on CI

[touilleMan]

Pytest's PostgreSQL tests:

• PostgreSQL12 ~9mn
• PostgreSQL 14: ~36mn !!!!

Currently we stick to 12 on the CI, but it requires ubuntu 20.04, so we should investigate this :/

[FirelightFlagboy]

If we don't want to be stuck to ubuntu-20.04 to install postgrelSQL which is provided by the defaults apt repositories, we can:

• Configure a docker container to run postgreSQL at the desired version
• Configure add the apt repositories of postgreSQL to the runner, documentation for ubuntu here

Both solution above allow to use another version of postgreSQL than the one provided by the default apt repositories

[FirelightFlagboy]

On a side note, since #2883 we use the postgreSQL APT repository to install postgre at the version 12