Typo @ `math/rational.{ceil}` doc example

[ariady-putra]

Ceil of 2/3 should be 1
https://aiken-lang.github.io/stdlib/aiken/math/rational.html#ceil

test math_rational_ceil() {
  [
    rational.new(1, 3) |> option.or_else(rational.zero()) |> rational.ceil(),
    rational.new(2, 3) |> option.or_else(rational.zero()) |> rational.ceil(),
    rational.new(3, 3) |> option.or_else(rational.zero()) |> rational.ceil(),
  ]
    |> list.all(fn(i) { i == 1 })
}

PASS [mem: 70972, cpu: 27449622] math_rational_ceil