Bump astro from 4.16.1 to 5.15.6 (#46)

Bumps [astro](https://github.com/withastro/astro/tree/HEAD/packages/astro) from 4.16.1 to 5.15.6.
- [Release notes](https://github.com/withastro/astro/releases)
- [Changelog](https://github.com/withastro/astro/blob/main/packages/astro/CHANGELOG-v4.md)
- [Commits](https://github.com/withastro/astro/commits/astro@5.15.6/packages/astro)

---
updated-dependencies:
- dependency-name: astro
  dependency-version: 5.15.6
  dependency-type: direct:production
...

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package.json

@@ -17,7 +17,7 @@
     "@astrojs/tailwind": "^5.1.0",
     "@markdoc/markdoc": "^0.4.0",
     "@tailwindcss/typography": "^0.5.9",
-    "astro": "^4.16.1",
+    "astro": "^5.15.6",
     "astro-markdoc-renderer": "0.0.1-alpha.1",
     "globby": "^13.2.2",
     "gray-matter": "^4.0.3",