fix: bump the security-updates group across 1 directory with 2 updates

Bumps the security-updates group with 2 updates in the / directory: [dompurify](https://github.com/cure53/DOMPurify) and [postcss](https://github.com/postcss/postcss).


Updates `dompurify` from 3.3.3 to 3.4.0
- [Release notes](https://github.com/cure53/DOMPurify/releases)
- [Commits](cure53/DOMPurify@3.3.3...3.4.0)

Updates `postcss` from 8.5.6 to 8.5.14
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.5.6...8.5.14)

---
updated-dependencies:
- dependency-name: dompurify
  dependency-version: 3.4.0
  dependency-type: direct:production
  dependency-group: security-updates
- dependency-name: postcss
  dependency-version: 8.5.14
  dependency-type: indirect
  dependency-group: security-updates
...

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

Author: dependabot[bot]