build(deps): bump astro in the astro-packages group (#310)

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


Updates `astro` from 5.17.1 to 5.18.0
- [Release notes](https://github.com/withastro/astro/releases)
- [Changelog](https://github.com/withastro/astro/blob/astro@5.18.0/packages/astro/CHANGELOG.md)
- [Commits](https://github.com/withastro/astro/commits/astro@5.18.0/packages/astro)

---
updated-dependencies:
- dependency-name: astro
  dependency-version: 5.18.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: astro-packages
...

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Author: dependabot[bot]