chore(deps): update postgres docker tag to v18

Author: renovate[bot]

docker-compose-bk.yml

@@ -11,7 +11,7 @@ services:
     links:
       - postgres-db
   postgres-db:
-    image: postgres:11.16
+    image: postgres:18.0
     restart: always
     environment:
       POSTGRES_PASSWORD: flex

docker-compose.yml

@@ -10,7 +10,7 @@ services:
     links:
       - postgres-db
   postgres-db:
-    image: postgres:11.16
+    image: postgres:18.0
     restart: always
     environment:
       POSTGRES_PASSWORD: flex