demo: We have not been testing against pg 9.6 and pg 10 for a while

[wolfgangwalther]

This was introduced in #2479 and ever since the following is happening:

% postgrest-with-postgresql-9.6 psql -c 'SELECT version()'
                                    version
--------------------------------------------------------------------------------
 PostgreSQL 11.21 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 12.3.0, 64-bit
(1 row)

% postgrest-with-postgresql-10 psql -c 'SELECT version()'
                                    version
-------------------------------------------------------------------------------
 PostgreSQL 11.21 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 12.3.0, 64-bit
(1 row)

So we have not been testing against v9.6 or v10.0 for more than a year now, but instead tested against v11 3x as much.

Locally, tests for both version started to fail after the change. It looks like there are only test-related failures, but I don't plan on fixing them. This PR is to serve as a demonstration only and I will pick up #2052 again.

[steve-chavez]

😮 We should test the output of select version() to prevent this from happening.

I'll fix the tests.

[wolfgangwalther]

I'll fix the tests.

That's not worth it. We agreed in #2052 (comment) to drop support for old pg versions one year after EOL. This is the case for both 9.6 and 10. I will follow through on that.

[wolfgangwalther]

Closing since this was just as a demonstration. Work on the issue is in #2052