Revert "chores(pgproto): use pure python impl of psycopg"

Summary

This is a fine example of clickbait, because in the next paragraph it says that libpq is still required (WTF).

In order to use the pure Python installation you will need the libpq installed in the system: for instance on Debian system you will probably need:

https://www.psycopg.org/psycopg3/docs/basic/install.html#pure-python-installation

• Revert "chores(pgproto): use pure python impl of psycopg"

This reverts commit 95807a30.

• Revert "chore: relock py deps to fix tomli installation"

This reverts commit 9f8687cd.