make the externa/exposed port configurable

defaults/main.yml

@@ -3,4 +3,5 @@
 postgres_password: t0t4l!S3cur1tY.
 postgres_data_folder: ./psql_data
 postgres_version: alpine
+postgres_external_port: 5432
 compose_dir: /srv

templates/docker-compose.yml.j2

@@ -12,6 +12,8 @@ services:
       POSTGRES_PASSWORD: {{ postgres_password }}
     volumes:
       - {{ postgres_data_folder }}:/var/lib/postgresql/data
+    ports:
+      - {{ postgres_external_port }}:5432
 
   adminer:
     image: adminer