Remove no-binary for psycopg2

[XanderVertegaal]

Psycopg is now on version 2.9, so the --no-binary flag can be removed (at least on my system).

The README suggests that we can use pip-sync instead of pip install -r requirements.txt for our yarn shortcut commands, but the note in CONTRIBUTING.md suggests that that is not the case, so I've left them as they are.

[jgonggrijp]

pip-sync is more reproducible because it also removes packages that we no longer depend on. However, I recall it not playing nice with deployment, so it's fine to leave the package.json as-is.