Update docker.io/library/postgres Docker tag to v18.2

dockhand/docker-compose.yml

@@ -1,7 +1,7 @@
 services:
   dockhand_db:
     container_name: dockhand_db
-    image: docker.io/library/postgres:18.1@sha256:1090bc3a8ccfb0b55f78a494d76f8d603434f7e4553543d6e807bc7bd6bbd17f
+    image: docker.io/library/postgres:18.2@sha256:b6b4d0b75c699a2c94dfc5a94fe09f38630f3b67ab0e1653ede1b7ac8e13c197
     restart: unless-stopped
     environment:
       - POSTGRES_USER=${POSTGRES_USER}