Research spike: Adding support for PG13

Overview

• Research the work required to add PostgreSQL 13 as opt in
• Time box 3 days
• Create issues to capture the work that needs to be done
• Link the issues to &3832 (closed)

Note the intent here is to ship PostgreSQL 13 as opt-in in %14.0 and have PostgreSQL 12 be the minimum required version and only other supported version besides PostgreSQL 13.

Issue used when researching the addition of PG 11: #4864 (closed)