Bump the npm_and_yarn at /. security update group with 3 updates (#3350)

Bumps the npm_and_yarn at /. security update group with 3 updates: [autoprefixer](https://github.com/postcss/autoprefixer), [cssnano](https://github.com/cssnano/cssnano) and [gulp-postcss](https://github.com/postcss/gulp-postcss).


Updates `autoprefixer` from 9.8.6 to 10.4.16
- [Release notes](https://github.com/postcss/autoprefixer/releases)
- [Changelog](https://github.com/postcss/autoprefixer/blob/main/CHANGELOG.md)
- [Commits](postcss/autoprefixer@9.8.6...10.4.16)

Updates `cssnano` from 4.1.10 to 6.0.1
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/[email protected])

Updates `gulp-postcss` from 8.0.0 to 9.0.1
- [Release notes](https://github.com/postcss/gulp-postcss/releases)
- [Commits](postcss/gulp-postcss@8.0.0...9.0.1)

---
updated-dependencies:
- dependency-name: autoprefixer
  dependency-type: direct:production
- dependency-name: cssnano
  dependency-type: direct:production
- dependency-name: gulp-postcss
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>