Bump postcss, next and stylelint

Bumps [postcss](https://github.com/postcss/postcss) to 8.4.38 and updates ancestor dependencies [postcss](https://github.com/postcss/postcss), [next](https://github.com/vercel/next.js) and [stylelint](https://github.com/stylelint/stylelint). These dependencies need to be updated together.


Updates `postcss` from 8.4.16 to 8.4.38
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.16...8.4.38)

Updates `next` from 12.3.0 to 14.2.3
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v12.3.0...v14.2.3)

Updates `stylelint` from 13.13.1 to 16.4.0
- [Release notes](https://github.com/stylelint/stylelint/releases)
- [Changelog](https://github.com/stylelint/stylelint/blob/main/CHANGELOG.md)
- [Commits](stylelint/stylelint@13.13.1...16.4.0)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: indirect
- dependency-name: next
  dependency-type: direct:production
- dependency-name: stylelint
  dependency-type: direct:development
...

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