The Postgres CI site only listed erpnext in install_apps, so the payments app
(fetched and built by install.sh via 'bench get-app payments') was never
installed on the site — leaving 'tabPayment Gateway' absent. test_payment_request
(and other payment-gateway-dependent tests) then errored on Postgres with
'relation "tabPayment Gateway" does not exist', while MariaDB passed because its
site_config already lists ["payments", "erpnext"]. Match that ordering for parity.