Update postgres install instructions

Dockerfile.ubuntu

@@ -2,9 +2,11 @@ FROM ubuntu:latest AS base
 
 ARG POSTGRES_VERSION=15
 
-RUN apt-get -y update && apt-get -y install lsb-release ca-certificates wget gnupg && \
-    echo "deb https://apt.postgresql.org/pub/repos/apt $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list && \
-    wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | apt-key add - && \
+RUN apt-get -y update && \
+    apt-get -y install curl ca-certificates lsb-release && \
+    install -d /usr/share/postgresql-common/pgdg && \
+    curl -o /usr/share/postgresql-common/pgdg/apt.postgresql.org.asc --fail https://www.postgresql.org/media/keys/ACCC4CF8.asc && \
+    sh -c 'echo "deb [signed-by=/usr/share/postgresql-common/pgdg/apt.postgresql.org.asc] https://apt.postgresql.org/pub/repos/apt $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list' && \
     apt-get -y update
 
 RUN apt-get -y install postgresql-client-$POSTGRES_VERSION

README.md

@@ -1,22 +1,24 @@
-# binaryoverload/postgresql-client 
-![GitHub Workflow Status (with event)](https://img.shields.io/github/actions/workflow/status/binaryoverload/docker-postgresql-client/docker.yml) [![Docker Hub](https://img.shields.io/badge/Docker%20Hub-gray?logo=docker)](https://hub.docker.com/r/binaryoverload/postgresql-client) [![GitHub](https://img.shields.io/badge/GitHub-black?logo=github&logoColor=white)](https://github.com/binaryoverload/docker-postgresql-client/)
+# binaryoverload/postgresql-client
 
+![GitHub Workflow Status (with event)](https://img.shields.io/github/actions/workflow/status/binaryoverload/docker-postgresql-client/docker.yml) [![Docker Hub](https://img.shields.io/badge/Docker%20Hub-gray?logo=docker)](https://hub.docker.com/r/binaryoverload/postgresql-client) [![GitHub](https://img.shields.io/badge/GitHub-black?logo=github&logoColor=white)](https://github.com/binaryoverload/docker-postgresql-client/)
 
 A Docker image for all of the PostgreSQL client executables, including:
- - `pg_dump` - Extract a PostgreSQL database into a script file or other archive file
- - `pg_dumpall` - Extract a PostgreSQL database cluster into a script file
- - `pg_restore` - Restore a PostgreSQL database from an archive file created by pg_dump
- - `psql` - PostgreSQL interactive terminal
- - `pg_isready` - Check the connection status of a PostgreSQL server
- - `pg_basebackup` - Take a base backup of a PostgreSQL cluster
- - `pg_verifybackup` - Verify the integrity of a base backup of a PostgreSQL cluster
- - [And many more...](https://www.postgresql.org/docs/current/reference-client.html)
+
+- `pg_dump` - Extract a PostgreSQL database into a script file or other archive file
+- `pg_dumpall` - Extract a PostgreSQL database cluster into a script file
+- `pg_restore` - Restore a PostgreSQL database from an archive file created by pg_dump
+- `psql` - PostgreSQL interactive terminal
+- `pg_isready` - Check the connection status of a PostgreSQL server
+- `pg_basebackup` - Take a base backup of a PostgreSQL cluster
+- `pg_verifybackup` - Verify the integrity of a base backup of a PostgreSQL cluster
+- [And many more...](https://www.postgresql.org/docs/current/reference-client.html)
 
 This image is intended to be used as a base image for running PostgreSQL scripts and as such is deployed in both Ubuntu (Default) and Alpine distro variants with all major supported versions:
- - 16
- - 15
- - 14
- - 13
- - 12
+
+- 16
+- 15
+- 14
+- 13 (Ubuntu only)
+- 12 (Ubuntu only)
 
 Information on the versions of PostgreSQL and their support periods can be found [at the link here](https://www.postgresql.org/support/versioning/).