Update dependency eslint to v9

Author: renovate[bot]

package.json

@@ -27,7 +27,7 @@
   },
   "devDependencies": {
     "chai": "4.2.0",
-    "eslint": "6.8.0",
+    "eslint": "9.25.1",
     "eslint-config-theme-next": "1.1.4",
     "hexo": "4.2.0",
     "mocha": "7.1.1",