Update in accordance to latest language-sass changes

Requirements

Filling out the template is required. Any pull request that does not include enough information to be reviewed in a timely manner may be closed at the maintainers' discretion.
All new code requires tests to ensure against regressions

Description of the Change

Really small change here. The tag scope is now entity.name.tag.css in Sass, without the trailing .sass. language-css is now also included in all the CSS-like grammars, so always activate it.

Alternate Designs

None.

Benefits

Ideally, none - everything will continue to function like before.

Possible Drawbacks

See Benefits.

Applicable Issues