fix(deps): update astro monorepo (#489)

This PR contains the following updates:

| Package | Change | [Age](https://docs.renovatebot.com/merge-confidence/) | [Confidence](https://docs.renovatebot.com/merge-confidence/) |
|---|---|---|---|
| [@astrojs/check](https://github.com/withastro/astro/tree/main/packages/language-tools/astro-check) ([source](https://github.com/withastro/astro/tree/HEAD/packages/language-tools/astro-check)) | [`0.9.6` → `0.9.7`](https://renovatebot.com/diffs/npm/@astrojs%2fcheck/0.9.6/0.9.7) | ![age](https://developer.mend.io/api/mc/badges/age/npm/@astrojs%2fcheck/0.9.7?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/@astrojs%2fcheck/0.9.6/0.9.7?slim=true) |
| [astro](https://astro.build) ([source](https://github.com/withastro/astro/tree/HEAD/packages/astro)) | [`5.18.0` → `5.18.1`](https://renovatebot.com/diffs/npm/astro/5.18.0/5.18.1) | ![age](https://developer.mend.io/api/mc/badges/age/npm/astro/5.18.1?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/astro/5.18.0/5.18.1?slim=true) |

---

### Release Notes

<details>
<summary>withastro/astro (@&#8203;astrojs/check)</summary>

### [`v0.9.7`](https://github.com/withastro/astro/blob/HEAD/packages/language-tools/astro-check/CHANGELOG.md#097)

[Compare Source](https://github.com/withastro/astro/compare/@astrojs/check@0.9.6...@astrojs/check@0.9.7)

##### Patch Changes

- [#&#8203;15187](withastro/astro#15187) [`bbb5811`](withastro/astro@bbb5811) Thanks [@&#8203;matthewp](https://github.com/matthewp)! - Update to Astro 6 beta

- [#&#8203;15198](withastro/astro#15198) [`55107a1`](withastro/astro@55107a1) Thanks [@&#8203;HiDeoo](https://github.com/HiDeoo)! - Updates to Astro 6 beta

- Updated dependencies \[[`bbb5811`](withastro/astro@bbb5811), [`df6d2d7`](withastro/astro@df6d2d7)]:
  - [@&#8203;astrojs/language-server](https://github.com/astrojs/language-server)@&#8203;2.16.1

</details>

<details>
<summary>withastro/astro (astro)</summary>

### [`v5.18.1`](https://github.com/withastro/astro/releases/tag/astro%405.18.1)

[Compare Source](https://github.com/withastro/astro/compare/astro@5.18.0...astro@5.18.1)

##### Patch Changes

- Updated dependencies \[[`c2cd371`](withastro/astro@c2cd371)]:
  - [@&#8203;astrojs/internal-helpers](https://github.com/astrojs/internal-helpers)@&#8203;0.7.6
  - [@&#8203;astrojs/markdown-remark](https://github.com/astrojs/markdown-remark)@&#8203;6.3.11

</details>

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package.json

@@ -1,15 +1,15 @@
 {
   "dependencies": {
     "@astrojs/starlight": "0.37.7",
-    "astro": "5.18.0",
+    "astro": "5.18.1",
     "katex": "0.16.38",
     "rehype-katex": "7.0.1",
     "remark-math": "6.0.0",
     "sharp": "0.34.5",
     "typescript": "5.9.3"
   },
   "devDependencies": {
-    "@astrojs/check": "0.9.6",
+    "@astrojs/check": "0.9.7",
     "@biomejs/biome": "2.4.6",
     "prettier": "3.8.1",
     "prettier-plugin-astro": "0.14.1"