build(deps): bump astro from 4.16.16 to 4.16.18

Bumps [astro](https://github.com/withastro/astro/tree/HEAD/packages/astro) from 4.16.16 to 4.16.18.
- [Release notes](https://github.com/withastro/astro/releases)
- [Changelog](https://github.com/withastro/astro/blob/astro@4.16.18/packages/astro/CHANGELOG.md)
- [Commits](https://github.com/withastro/astro/commits/astro@4.16.18/packages/astro)

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

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

package.json

@@ -13,7 +13,7 @@
     "@interledger/docs-design-system": "^0.5.4",
     "@types/react": "^19.0.1",
     "@types/react-dom": "^19.0.2",
-    "astro": "4.16.16",
+    "astro": "4.16.18",
     "astro-i18next": "^1.0.0-beta.21",
     "prettier": "^3.4.2",
     "prism-react-renderer": "^2.4.1",