How to Install postgresql-client-11 on Ubuntu 18.04?

on ubuntu 18.04, I'm trying to upgrade pg client, to v11 (although open to
greater versions assuming backward compatibility) to get around this issue:
pg_dump: server version: 11.10; pg_dump version: 9.3.24
pg_dump: aborting because of server version mismatch

my steps so far have been to follow the quickstart from here:
https://wiki.postgresql.org/wiki/Apt , which is..:

Import the repository key from
*https://www.postgresql.org/media/keys/ACCC4CF8.asc
<https://www.postgresql.org/media/keys/ACCC4CF8.asc>*:

sudo apt install curl ca-certificates gnupg
curl https://www.postgresql.org/media/keys/ACCC4CF8.asc | gpg
--dearmor | sudo tee /etc/apt/trusted.gpg.d/apt.postgresql.org.gpg
>/dev/null

Create */etc/apt/sources.list.d/pgdg.list*. The distributions are called
*codename**-pgdg*. In the example, replace *buster* with the actual
distribution you are using. File contents:

deb http://apt.postgresql.org/pub/repos/apt *buster*-pgdg main

(You may determine the codename of your distribution by running *lsb_release
-c*). For a script version of the above file creation, presuming you are
using a supported release:

sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt
$(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'

Finally, update the package lists, and start installing packages:

sudo apt update

and from here:

sudo apt install postgresql-client-11

However I get:
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package postgresql-11

is client v11 supported on ubuntu 18.04? If yes, does anyone have steps?

--
-John