Bump postcss and @redocly/cli

Removes [postcss](https://github.com/postcss/postcss). It's no longer used after updating ancestor dependency [@redocly/cli](https://github.com/Redocly/redocly-cli). These dependencies need to be updated together.


Removes `postcss`

Updates `@redocly/cli` from 2.25.3 to 2.30.5
- [Release notes](https://github.com/Redocly/redocly-cli/releases)
- [Commits](https://github.com/Redocly/redocly-cli/compare/@redocly/cli@2.25.3...@redocly/cli@2.30.5)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 
  dependency-type: indirect
- dependency-name: "@redocly/cli"
  dependency-version: 2.30.5
  dependency-type: direct:production
...

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

Author: dependabot[bot]