Use a volume for postgres data in docker-compose.dev.yml

docker-compose.dev.yml

@@ -40,5 +40,10 @@ services:
     image: "postgres:11"
     ports:
       - "5432:5432"
+    volumes:
+      - data-volume:/var/lib/postgres/data
     environment:
       - POSTGRES_PASSWORD=8JN4w0UsN5dbjMjNvPe452P2yYOqg5PV
+
+volumes:
+  data-volume: