Update dependency eslint to ~9.21.0

Author: renovate[bot]

package.json

@@ -32,7 +32,7 @@
   },
   "devDependencies": {
     "doctoc": "^2.0.0",
-    "eslint": "~9.19.0",
+    "eslint": "~9.21.0",
     "prettier": "^3.0.0"
   },
   "peerDependencies": {