Subqueries in Update().Set() with Postgres dialect generates incorrect query

[afv1]

Describe the bug
Subqueries in Update().Set() with Postgres dialect generates incorrect query: '?' instead of '$1'

To Reproduce

testDS := goqu.Dialect("postgres").Update("test.table_1").
	Set(goqu.Record{
		"sub": goqu.Select("id").
			From("test.table_1").
			Where(goqu.C("from").Eq(from)),
	}).
	From("test.table_2").
	Where(
		goqu.C("test_id").Eq(id),
		goqu.C("to").Eq(to),
	)

fmt.Println(testDS.Prepared(true).ToSQL())
	
// Output:
// UPDATE "test"."table_1" SET "sub"=(SELECT "id" FROM "test"."table_1" WHERE ("from" = ?)) FROM "test"."table_2"
// WHERE (("test_id" = $2) AND ("to" = $3)) [1 12 2] <nil>

Expected behavior
Expected output:

UPDATE "test"."table1" SET "huy"=(SELECT "id" FROM "t"."subtable_1" WHERE ("from" = $1)) FROM "test"."table_2" WHERE (("test_id" = $2) AND ("to" = $3)) [1 12 2] <nil>

But first parameter interpolated incorrectly for PG syntax '?'. Looks like it caused by sybquery in Setect(...)

Dialect:

• postgres
• mysql
• sqlite3

Additional context
Add any other context about the problem here.