Replace `purrr::cross2()` with `tidyr::expand_grid()`

[gvelasq]

Warning (test-tab.R:60:3): tab1() and tab2() work
`cross2()` was deprecated in purrr 1.0.0.
i Please use `tidyr::expand_grid()` instead.
i See <https://github.com/tidyverse/purrr/issues/768>.

Related: tidyverse/purrr#768

[lhdjung]

Hi, I saw that you currently use purrr::cross2() to create the tab_sequence object in tab2(). PR 26c090a replaces cross2() by tidyr::expand_grid(), but this new function currently returns its output in a different order than cross2().

If tab_sequence should retain its current order, there are a few options:

• The dev version of tidyr allows users to opt into ordering like cross2().
• vctrs::vec_expand_grid() underlies the tidyr solution, but you could use it directly.
• base::expand.grid() also orders like cross2(), but it is importantly different from tidyr::expand_grid() in other ways; see linked docs.

Also, the linked PR passes .filter = filter to tidyr::expand_grid(), but the function has no such parameter, so this won't work.