invalid connection option "query_lookup"

this change fixes to error when using pgsql driver.

Could not instantiate PDO with DSN "pgsql:query_lookup=SELECT password FROM mailbox WHERE username = %u and active = 1;query_modify=UPDATE mailbox SET password = %e WHERE username = %u;host=localhost;dbname=postfix".  PDOException: SQLSTATE[08006] [7] invalid connection option "query_lookup"