chore: Add psycopg 2.9.10 into requirements-test.txt

[rhatgadkar-goog]

psycopg 2.9.10 is supported on Python 3.13 for Windows now: psycopg/psycopg2#1736. So we can add psycopg 2.9.10 into requirements-test.txt.

This change does the following:

• Add psycopg2 into requirement-tests.txt.
• In tests.yml, run the Python 3.13 unit tests on macos-latest, but run the Python 3.9 unit tests only on macos-12.
• Fix the lint issue about enum member annotation: https://mypy.readthedocs.io/en/stable/changelog.html#change-to-enum-membership-semantics.
• Move test_psycopg2_direct_connection.py back into tests/system folder because it can now run since psycopg2 is in requirements-test.txt.

[rhatgadkar-goog]

@enocom After this change is merged, can we remove the branch protection setting on unit tests (macos-latest, 3.9) and add one for unit tests (macos-12, 3.9)?

[enocom]

You'll have to change the branch protection settings before merging this.

[enocom]

Thanks for cleaning this up.

[enocom]

Small note: this is a "chore" since there's no meaningful user facing feature (right?).

[rhatgadkar-goog]

Small note: this is a "chore" since there's no meaningful user facing feature (right?).

Thanks. Yes, that makes sense

[rhatgadkar-goog]

Had to make a small change to this that requires approval. The macos-12 runner is not supported anymore: actions/runner-images#10721. So the unit tests (macos-12, 3.9) test was failing. I instead modified requirements-test.txt to install psycopg 2.9.9 on Python 3.9 for MacOS.