actions: use Debians's script for adding the Postgres apt repo

.github/actions/setup-postgresql/action.yml

@@ -11,10 +11,8 @@ runs:
     steps:
         - name: Remove existing PostgreSQL
           run: |
+              sudo /usr/share/postgresql-common/pgdg/apt.postgresql.org.sh -y
               sudo apt-get purge -yq postgresql*
-              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
-              sudo sh -c 'echo "deb https://apt.postgresql.org/pub/repos/apt $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'
               sudo apt-get update -qq
 
           shell: bash