Released 2024-05-19.
Progress: 5803 of 7673 tests passed.

* Improved support for the `selector.nest` function (PR #189).
* Moved `selector.append` to new selector implementation (PR #190).
* Implemented the `selector.simple-selectors` function (PR #191).
* Implemented the `selector.extend` function, except some of the more
  complicated corner cases (PR #194).
* Parse next-generation css selectors directly (rather than parsing as
  the old type and converting to the new).  Fixes the `selector.parse`
  function and improves support for other selector functions (PR #192).
* Some internal cleanup and improvements in the next-generation css
  selector implementation (which is currently internal and used only
  for selector functions, but should replace the old css selector
  implementation in release 0.29).
* Improvements in css-compatible functions that is evaluated if
  possible, but kept as css if the arguments _may_ make sense in a
  browser (PR #193).
* Improved no-args `math.random`, it now returns a f64 number.
* Some other minor code cleanup.
* MSRV is now 1.74 for rsass-cli (and still 1.61 for the lib and macros).
* Updated sass-spec test suite to 2024-05-16.