Explicit supported Postgres version

[ewjoachim]

Currently:

• We're not making explicit the supported PG versions
• We're not testing the supported versions

I definitely don't want to make a cartesian product of supported python and Postgres because this will take forever to run (plus, there IS an ecological impact to all those things...). I think oldest python + all supported Postgres and oldest Postgres + all supported pythons (one line and one column)

For now I guess either we support all supported Postgres versions.

[kasteph]

@ewjoachim I think support should only be provided for PG11 and up.

PG10 support ended ~1.5 years ago and according to a survey by Timescale, only 12% of PG10 or older is used in production (granted it's of 888 samples only).

https://www.postgresql.org/support/versioning/
https://www.timescale.com/state-of-postgres/2023

[ewjoachim]

Note that this ticket is 4 years old. Of course, we should keep the latest versions, what we should keep changes through time.

(https://endoflife.date/postgresql presents the same info, and I find it more readable)