Change docker-compose port to 5432 (#402)

Change the Postgres port number to the default `5432` in
`docker-compose.yml`.

Author: andrew-farries

docker-compose.yml

@@ -6,6 +6,6 @@ services:
       - POSTGRES_USER=postgres
       - POSTGRES_PASSWORD=postgres
     ports:
-      - '6432:5432'
+      - '5432:5432'
     volumes: 
       - /var/lib/postgresql/data