chore(deps): bump astro in /doc in the npm-dependencies group (#328)

Bumps the npm-dependencies group in /doc with 1 update: [astro](https://github.com/withastro/astro/tree/HEAD/packages/astro).


Updates `astro` from 6.4.6 to 6.4.8
- [Release notes](https://github.com/withastro/astro/releases)
- [Changelog](https://github.com/withastro/astro/blob/astro@6.4.8/packages/astro/CHANGELOG.md)
- [Commits](https://github.com/withastro/astro/commits/astro@6.4.8/packages/astro)

---
updated-dependencies:
- dependency-name: astro
  dependency-version: 6.4.8
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: npm-dependencies
...

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Author: dependabot[bot]

doc/package.json

@@ -16,7 +16,7 @@
     "@astrojs/starlight": "^0.40.0",
     "@astrojs/starlight-markdoc": "^0.6.0",
     "@catppuccin/starlight": "^2.0.1",
-    "astro": "^6.4.6",
+    "astro": "^6.4.8",
     "sharp": "^0.35.1",
     "starlight-llms-txt": "^0.10.0",
     "typescript": "^6.0.3"