chore(deps): update dependency eslint to v8 (#563)

Co-authored-by: Takashi Matsuo <tmatsuo@google.com>

Author: renovate-bot

package.json

@@ -4,7 +4,7 @@
   "description": "End to end samples for running Node.js applications on Google Cloud Platform",
   "dependencies": {},
   "devDependencies": {
-    "eslint": "^7.1.0",
+    "eslint": "^8.0.0",
     "eslint-config-prettier": "^8.0.0",
     "eslint-plugin-node": "^11.1.0",
     "eslint-plugin-prettier": "^4.0.0",