Test with multiple drivers

[prochac]

The integtest pkg uses github.com/jackc/pgx/v4/stdlib, while we actually use v5 in production. The versions are mostly compatible, but may have some small nuances.

The tested versions should be:

• github.com/lib/pq
• github.com/jackc/pgx/v4/stdlib
• github.com/jackc/pgx/v5/stdlib
• ... next releases of pgx

Import pgx driver using driverName with version included https://github.com/jackc/pgx/issues/1480

Keep the usage of drivers inside integrtest pkg, this helps Go reduce dependencies. Go 1.21 (I think) does some smart "dependency-shaking"