mount postgres folder to local directory by default (#8443)

docker/docker-compose.yml

@@ -69,9 +69,8 @@ services:
       POSTGRES_USER: ${DB_USERNAME}
       POSTGRES_DB: ${DB_DATABASE_NAME}
     volumes:
-      - pgdata:/var/lib/postgresql/data
+      - ${DB_DATA_LOCATION}:/var/lib/postgresql/data
     restart: always
 
 volumes:
-  pgdata:
   model-cache:

docker/example.env

@@ -14,5 +14,6 @@ DB_PASSWORD=postgres
 DB_HOSTNAME=immich_postgres
 DB_USERNAME=postgres
 DB_DATABASE_NAME=immich
+DB_DATA_LOCATION=./postgres
 
 REDIS_HOSTNAME=immich_redis