Dart-sass

* No user-visible changes.

* No user-visible changes.

* Stop supporting non-LTS Node.js versions.

* Fix a bug in `string.insert` with certain negative indices.

JS API

* Add support for the `sourceMapIncludeSources` option in the new JS API.

TypeScript Declarations

* Fix a bug where `LegacyPluginThis.options.linefeed` was typed to return
abbreviations when it actually returned literal linefeed characters.

JS API

* **Potentially breaking bug fix:** Match the specification of the new JS API by
setting `LegacyResult.map` to `undefined` rather than `null`.

TypeScript Declarations

* Add a declaration for the `NULL` constant.

JS API

TypeScript Declarations

* Add declarations for the `TRUE` and `FALSE` constants.