Bump postcss, next and postcss-preset-env

Bumps [postcss](https://github.com/postcss/postcss) to 8.4.47 and updates ancestor dependencies [postcss](https://github.com/postcss/postcss), [next](https://github.com/vercel/next.js) and [postcss-preset-env](https://github.com/csstools/postcss-plugins/tree/HEAD/plugin-packs/postcss-preset-env). These dependencies need to be updated together.


Updates `postcss` from 7.0.36 to 8.4.47
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@7.0.36...8.4.47)

Updates `next` from 12.3.0 to 15.0.2
- [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...v15.0.2)

Updates `postcss-preset-env` from 6.7.0 to 10.0.8
- [Changelog](https://github.com/csstools/postcss-plugins/blob/main/plugin-packs/postcss-preset-env/CHANGELOG.md)
- [Commits](https://github.com/csstools/postcss-plugins/commits/HEAD/plugin-packs/postcss-preset-env)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: indirect
- dependency-name: next
  dependency-type: direct:production
- dependency-name: postcss-preset-env
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]