chore(deps): bump astro from 4.5.12 to 4.15.1 in /site

Bumps [astro](https://github.com/withastro/astro/tree/HEAD/packages/astro) from 4.5.12 to 4.15.1.
- [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@4.15.1/packages/astro)

---
updated-dependencies:
- dependency-name: astro
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

site/package.json

@@ -11,7 +11,7 @@
   },
   "dependencies": {
     "@astrojs/starlight": "^0.21.3",
-    "astro": "^4.5.12",
+    "astro": "^4.15.1",
     "sharp": "^0.33.2",
     "@astrojs/check": "^0.8.1",
     "typescript": "^5.4.4"