Better idea: just install the Postgres extension that enables ISO SQL Temporal Tables, just like what MSSQL and MariaDB have had for 8 years now: https://pgxn.org/dist/temporal_tables/
Separately though, it's great to see that there's still people trying to solve this problem at the extension level for Postgres. I was sad to discover that Postgres for a very long time had an official extension for time travel - https://www.postgresql.org/docs/11/contrib-spi.html#id-1.11.... - only to realize that it had been removed in https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit... - with a note that "it's easy to implement this separately" but no real hints that anyone was taking up the mantle.
As a simpler alternative, if you're only modifying data via Django and can tolerate some unreliability, https://django-simple-history.readthedocs.io/en/latest/ can get you much of the way there without a need for extensions. We've built on top of it with some domain-specific modifications to visualize and filter diffs, giving us at least a best-efforts audit-esque log system.
https://mariadb.com/kb/en/temporal-tables/
A quick Google turns up nothing for MySQL temporal.