chore(deps): update postgres docker tag to v18

Author: renovate[bot]

.github/workflows/test.yml

@@ -25,7 +25,7 @@ jobs:
             database: nextcloud
             port: 3306
           - name: pgsql
-            image: postgres:17
+            image: postgres:18
             username: postgres
             database: postgres
             port: 5432