Bump the twentynineteen-css-sass group

Bumps the twentynineteen-css-sass group in /src/wp-content/themes/twentynineteen with 3 updates: [@wordpress/browserslist-config](https://github.com/WordPress/gutenberg/tree/HEAD/packages/browserslist-config), [autoprefixer](https://github.com/postcss/autoprefixer) and [postcss-focus-within](https://github.com/csstools/postcss-plugins/tree/HEAD/plugins/postcss-focus-within).


Updates `@wordpress/browserslist-config` from 6.34.0 to 6.39.0
- [Release notes](https://github.com/WordPress/gutenberg/releases)
- [Changelog](https://github.com/WordPress/gutenberg/blob/trunk/packages/browserslist-config/CHANGELOG.md)
- [Commits](https://github.com/WordPress/gutenberg/commits/@wordpress/browserslist-config@6.39.0/packages/browserslist-config)

Updates `autoprefixer` from 10.4.22 to 10.4.24
- [Release notes](https://github.com/postcss/autoprefixer/releases)
- [Changelog](https://github.com/postcss/autoprefixer/blob/main/CHANGELOG.md)
- [Commits](postcss/autoprefixer@10.4.22...10.4.24)

Updates `postcss-focus-within` from 9.0.1 to 10.0.0
- [Changelog](https://github.com/csstools/postcss-plugins/blob/main/plugins/postcss-focus-within/CHANGELOG.md)
- [Commits](https://github.com/csstools/postcss-plugins/commits/HEAD/plugins/postcss-focus-within)

---
updated-dependencies:
- dependency-name: "@wordpress/browserslist-config"
  dependency-version: 6.39.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
  dependency-group: twentynineteen-css-sass
- dependency-name: autoprefixer
  dependency-version: 10.4.24
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: twentynineteen-css-sass
- dependency-name: postcss-focus-within
  dependency-version: 10.0.0
  dependency-type: direct:development
  update-type: version-update:semver-major
  dependency-group: twentynineteen-css-sass
...

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Author: dependabot[bot]