chore(deps): bump markdown-it and @rocket/cli

Removes [markdown-it](https://github.com/markdown-it/markdown-it). It's no longer used after updating ancestor dependency [@rocket/cli](https://github.com/modernweb-dev/rocket/tree/HEAD/packages/cli). These dependencies need to be updated together.


Removes `markdown-it`

Updates `@rocket/cli` from 0.10.2 to 0.21.0
- [Release notes](https://github.com/modernweb-dev/rocket/releases)
- [Commits](https://github.com/modernweb-dev/rocket/commits/@rocket/launch@0.21.0/packages/cli)

---
updated-dependencies:
- dependency-name: "@rocket/cli"
  dependency-version: 0.21.0
  dependency-type: direct:production
- dependency-name: markdown-it
  dependency-version:
  dependency-type: indirect
...

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Author: dependabot[bot]