chore(website): update dependency astro to v5.12.8 (#7524)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

Author: renovate[bot]

site/package-lock.json

@@ -18,7 +18,7 @@
   "dependencies": {
     "@astrojs/starlight": "0.35.2",
     "@bugsnag/js": "8.4.0",
-    "astro": "5.12.6",
+    "astro": "5.12.8",
     "markdown-magic": "2.6.1",
     "sharp": "0.34.3",
     "strip-ansi": "7.1.0"