chore(deps): bump the site group across 1 directory with 3 updates

Bumps the site group with 3 updates in the /site directory: [@astrojs/markdown-remark](https://github.com/withastro/astro/tree/HEAD/packages/markdown/remark), [@astrojs/starlight](https://github.com/withastro/starlight/tree/HEAD/packages/starlight) and [astro](https://github.com/withastro/astro/tree/HEAD/packages/astro).


Updates `@astrojs/markdown-remark` from 7.2.4 to 7.3.1
- [Release notes](https://github.com/withastro/astro/releases)
- [Changelog](https://github.com/withastro/astro/blob/main/packages/markdown/remark/CHANGELOG.md)
- [Commits](https://github.com/withastro/astro/commits/@astrojs/markdown-remark@7.3.1/packages/markdown/remark)

Updates `@astrojs/starlight` from 0.41.10 to 0.42.1
- [Release notes](https://github.com/withastro/starlight/releases)
- [Changelog](https://github.com/withastro/starlight/blob/main/packages/starlight/CHANGELOG.md)
- [Commits](https://github.com/withastro/starlight/commits/@astrojs/starlight@0.42.1/packages/starlight)

Updates `astro` from 7.2.9 to 7.3.3
- [Release notes](https://github.com/withastro/astro/releases)
- [Changelog](https://github.com/withastro/astro/blob/main/packages/astro/CHANGELOG.md)
- [Commits](https://github.com/withastro/astro/commits/astro@7.3.3/packages/astro)

---
updated-dependencies:
- dependency-name: "@astrojs/markdown-remark"
  dependency-version: 7.3.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: site
- dependency-name: "@astrojs/starlight"
  dependency-version: 0.42.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: site
- dependency-name: astro
  dependency-version: 7.3.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: site
...

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

Author: dependabot[bot]