Update dependency eslint to v9

Author: renovate[bot]

package.json

@@ -15,7 +15,7 @@
   },
   "devDependencies": {
     "bunyan": "1.8.15",
-    "eslint": "7.21.0",
+    "eslint": "9.25.0",
     "eslint-plugin-ghost": "2.0.0",
     "mkdirp": "1.0.4",
     "mocha": "8.3.0",