npm: bump markdown-it

Bumps the npm_and_yarn group with 1 update in the /vscode-extension-self-contained directory: [markdown-it](https://github.com/markdown-it/markdown-it).


Updates `markdown-it` from 14.1.1 to 14.2.0
- [Changelog](https://github.com/markdown-it/markdown-it/blob/master/CHANGELOG.md)
- [Commits](markdown-it/markdown-it@14.1.1...14.2.0)

---
updated-dependencies:
- dependency-name: markdown-it
  dependency-version: 14.2.0
  dependency-type: indirect
  dependency-group: npm_and_yarn
...

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Author: dependabot[bot]