chore(deps): update postgres docker tag to v18 (#67)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Thor Tudal Lauridsen <30320530+thorlauridsen@users.noreply.github.com>

Author: renovate[bot]

docker-compose.yml

@@ -1,6 +1,6 @@
 services:
   postgres:
-    image: postgres:17
+    image: postgres:18
     container_name: postgres
     environment:
       POSTGRES_USER: postgres