chore(deps): update postgres docker tag to v18

Author: renovate[bot]

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
       # Label used to access the service container
       db:
         # Docker Hub image
-        image: postgres:12.22
+        image: postgres:18.1
         # Set health checks to wait until postgres has started
         options: >-
           --health-cmd pg_isready

docker-compose.services.yml

@@ -10,7 +10,7 @@ services:
   db:
     profiles:
       - backend
-    image: postgres:16
+    image: postgres:18
     healthcheck:
       test: ["CMD", "pg_isready"]
       interval: 3s