rsample 1.0.0

• Fixed how nested_cv() handles call objects so variables in the environment can be used when specifying resampling schemes (#81).

• Updated to testthat 3e (#280) and added better checking for vfold_cv() (#293).

• Finally removed the gather() method for rset objects. Use tidyr::pivot_longer() instead (#280).

• Changed initial_split() to avoid calling tidyselect twice on strata (#296). This fix stops initial_split() from generating messages like:

  Note: Using an external vector in selections is ambiguous.
  i Use `all_of(strata)` instead of `strata` to silence this message.
  i See <https://tidyselect.r-lib.org/reference/faq-external-vector.html>.

• Added better printing methods for initial split objects.