Postgres 13

[jarydkrish]

Now that Postgres 13 is generally available on Heroku, do the postgres client binaries need to be updated?

We are having an issue with Heroku CI builds failing due to a version mismatch when restoring from a Rails structure.sql file:

pg_dump: error: server version: 13.1 (Ubuntu 13.1-1.pgdg20.04+1); pg_dump version: 12.5 (Ubuntu 12.5-1.pgdg20.04+1)
       pg_dump: error: aborting because of server version mismatch
       rake aborted!
       failed to execute:
       pg_dump --schema-only --no-privileges --no-owner --file /app/db/structure.sql

This pull request updated the client binaries to Postgres 12: #151

Is something similar needed to support Postgres 13?