Update postgres Docker tag to v16.8

Author: renovate[bot]

Diff for: docker-compose.yml

@@ -19,7 +19,7 @@ services:
   postgres:
     ports:
       - 5432:5432
-    image: postgres:16.2-alpine
+    image: postgres:16.8-alpine
     restart: always
     environment:
       POSTGRES_PASSWORD: postgres