chore: Upgrade PostgreSQL to 12.7

https://www.postgresql.org/docs/release/12.7/

postgres/.env

@@ -1,6 +1,3 @@
-POSTGRES_IMAGE=postgres:12.5-alpine
 POSTGRES_USER=user-example
 POSTGRES_PASSWORD=password-example
 POSTGRES_DB=postgres-database-name-example
-POSTGRES_CONTAINER_NAME=postgres
-POSTGRES_VOLUME_NAME=postgres

postgres/docker-compose.yml

@@ -2,17 +2,17 @@ version: "3.8"
 
 volumes:
   postgres:
-    name: ${POSTGRES_VOLUME_NAME}
+    name: ${POSTGRES_VOLUME_NAME:-postgres}
 
 services:
   postgres:
-    container_name: ${POSTGRES_CONTAINER_NAME}
-    image: ${POSTGRES_IMAGE}
+    container_name: ${POSTGRES_CONTAINER_NAME:-postgres}
+    image: ${POSTGRES_IMAGE:-postgres:12.7-alpine}
     restart: always
     environment:
-      POSTGRES_USER: ${POSTGRES_USER}
-      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
-      POSTGRES_DB: ${POSTGRES_DB}
+      POSTGRES_USER: ${POSTGRES_USER:?err}
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:?err}
+      POSTGRES_DB: ${POSTGRES_DB:?err}
     volumes:
       - postgres:/var/lib/postgresql/data
       - /etc/timezone:/etc/timezone:ro