Update dependency stylelint to v16.21.1

Author: renovate[bot]

package.json

@@ -43,7 +43,7 @@
     "hexo-renderer-marked": "7.0.1",
     "js-yaml": "4.1.0",
     "mocha": "11.5.0",
-    "stylelint": "16.20.0",
+    "stylelint": "16.21.1",
     "stylelint-stylus": "1.0.0"
   }
 }