Instal psycopg2 2.8.x for unit testing on certain versions of Django.
Review Request #12279 — Created May 14, 2022 and submitted
There's an incompatibility between psycopg2 2.9 and higher for Postgres
support on Django 1.11 through 3.0. This change fixes up the tox
configuration to install 2.8.x on these versions.
Built all new tox environments for all versions of Django. All unit tests
pass for all Django versions for Postgres.