Fix SQL multiply of 2 bind params in multiline demo for PostgreSQL

[mvorisek]

Atk4\Data\Persistence\Sql\ExecuteException [code: 7]:
ERROR: operator is not unique: unknown * unknown
LINE 1: ..._box", $7 * $8 "atk_...
HINT:  Could not choose a best candidate operator. You might need to add explicit type casts.
query:
select (-1) "atk_fp_multiline_item__id",
    'Chocolate' "atk_fp_multiline_item__item",
    '2020-02-20' "atk_fp_multiline_item__inv_date",
    '07:20:00.000000' "atk_fp_multiline_item__inv_time",
    80 "atk_fp_multiline_item__country_id",
    0 "atk_fp_multiline_item__qty",
    5 "atk_fp_multiline_item__box",
    0 * 5 "atk_fp_multiline_item__total_sql",
    NULL "atk_fp_multiline_item__total_php"
from "multiline_item" limit 1 offset 0

related with atk4/data#989

the problem is type info is not avaialbe before the SQL bind params are passed, but PostgreSQL needs the type info earlier