Switch to psycopg3

[edgarrmondragon]

• Use https://github.com/psycopg/psycopg (and https://docs.sqlalchemy.org/en/20/dialects/postgresql.html#module-sqlalchemy.dialects.postgresql.psycopg)
• Instead of https://github.com/psycopg/psycopg2/

[SpaceCondor]

@edgarrmondragon @visch @kinghuang Would this simplify the PR for the copy command? #370

psycopg3 supports the copy command without files: https://www.psycopg.org/psycopg3/docs/basic/copy.html

[edgarrmondragon]

@edgarrmondragon @visch @kinghuang Would this simplify the PR for the copy command? #370

psycopg3 supports the copy command without files: https://www.psycopg.org/psycopg3/docs/basic/copy.html

Maybe. It's at least worth trying. There's also the recent suggestion in #370 (comment).