Cap the version of the psycopg2-binary dependency for Postgres.

Review Request #2264 — Created Sept. 23, 2021 and updated

Review Board

`psycopg2-binary` 2.9 introduced some changes that broke timezone
management on older versions of Django (2.2 and older). This includes
us, and is described at

Official guidance is to pin the version, so to avoid customer issues,
our wrapper package now pins `psycopg2-binary` to `<2.9`.

Testing Done:
Tested that installing `ReviewBoard[postgres]` installed the right package.

Verified the fix with a customer. zklllllllllllllllllll

Reviewed at