This project is officially deprecated, but its functionality has recently risen like a phoenix from the ashes in results
Version 3.0.1663481299 (from Sep 18, 2022) was the final release, and there will be no further releases.
migra
was a schema diff tool for PostgreSQL, written in Python. You could use it in your python scripts, or from the command line like this:
$ migra postgresql:///a postgresql:///b
alter table "public"."products" add column newcolumn text;
alter table "public"."products" add constraint "x" CHECK ((price > (0)::numeric));
migra
magically figured out all the statements required to get from A to B.