chore(deps): update dependency webpack to v5 (#398)

Author: renovate-bot

packages/google-cloud-iot/package.json

@@ -65,7 +65,7 @@
     "sinon": "^9.0.1",
     "ts-loader": "^8.0.0",
     "typescript": "^3.8.3",
-    "webpack": "^4.41.2",
+    "webpack": "^5.0.0",
     "webpack-cli": "^4.0.0"
   }
 }