fix: use Docker network for postgres, set PGHOST to avoid port conflicts

.forgejo/workflows/ci.yml

@@ -17,8 +17,6 @@ jobs:
           POSTGRES_PASSWORD: postgres
           POSTGRES_USER: postgres
           POSTGRES_DB: aprsme_test
-        ports:
-          - 5432:5432
         options: >-
           --health-cmd "pg_isready -U postgres"
           --health-interval 10s
@@ -27,6 +25,7 @@ jobs:
     env:
       MIX_ENV: test
       ImageOS: ubuntu24
+      PGHOST: postgres
 
     steps:
       - name: Configure git for submodules