fix(deps): update dependency astro to v4.15.3

Author: renovate[bot]

bun.lockb

@@ -19,7 +19,7 @@
   },
   "dependencies": {
     "@astrojs/starlight": "0.26.3",
-    "astro": "4.15.2",
+    "astro": "4.15.3",
     "sharp": "0.33.5"
   },
   "devDependencies": {