postgresql – Stops connections to aurora postgres database

I'm working on upgrading my Aurora Postgres database from 1.3 (page 9.6) to 2.2 (10.6). And since no major upgrade is supported, I plan to take pg_dump and restore it to the latest version of the database. Because the database is large, pg_dump takes a few hours to run and assumes that the restore will take the same amount of time. As long as dump and restore do not occur, I do not want a user to be able to connect to the database until the upgrade is complete? Without pg_hba.conf file, what are my options to block users' access? One option I could think of is to revoke the user's login on all dbs, another option?