Bump astro from 5.15.3 to 5.15.4 (#622)

Bumps [astro](https://github.com/withastro/astro/tree/HEAD/packages/astro) from 5.15.3 to 5.15.4.
- [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/[email protected]/packages/astro)

---
updated-dependencies:
- dependency-name: astro
  dependency-version: 5.15.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package-lock.json

@@ -14,7 +14,7 @@
   },
   "dependencies": {
     "@astrojs/starlight": "^0.36.2",
-    "astro": "^5.15.3",
+    "astro": "^5.15.4",
     "rehype-callouts": "^2.1.2",
     "remark-obsidian-callout": "^1.5.1",
     "sharp": "^0.34.4",