Check postgres availability through network port

The pg_isready returns true earlier if tested through the local socket.
I have added the '-h postgres' flag, to test availability throught the
network port.

tests/docker-compose.yml

@@ -5,7 +5,7 @@ services:
       POSTGRES_USER: &pguser odoo
       POSTGRES_PASSWORD: &pgpassword odoo
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready"]
+      test: ["CMD-SHELL", "pg_isready -h postgres"]
       interval: 5s
       timeout: 5s
       retries: 5