Bump markdown-it and @11ty/eleventy in /site

Bumps [markdown-it](https://github.com/markdown-it/markdown-it) to 14.1.1 and updates ancestor dependency [@11ty/eleventy](https://github.com/11ty/eleventy). These dependencies need to be updated together.


Updates `markdown-it` from 13.0.1 to 14.1.1
- [Changelog](https://github.com/markdown-it/markdown-it/blob/master/CHANGELOG.md)
- [Commits](markdown-it/markdown-it@13.0.1...14.1.1)

Updates `@11ty/eleventy` from 2.0.1 to 3.1.2
- [Release notes](https://github.com/11ty/eleventy/releases)
- [Changelog](https://github.com/11ty/eleventy/blob/main/docs/release-instructions.md)
- [Commits](11ty/eleventy@v2.0.1...v3.1.2)

---
updated-dependencies:
- dependency-name: markdown-it
  dependency-version: 14.1.1
  dependency-type: indirect
- dependency-name: "@11ty/eleventy"
  dependency-version: 3.1.2
  dependency-type: direct:development
...

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Author: dependabot[bot]