Bump webpack-dev-server from 2.11.5 to 3.10.3 in /packages/react-json-tree/examples (#512)

Author: dependabot[bot]

packages/react-json-tree/examples/package.json

@@ -33,7 +33,7 @@
     "babel-plugin-transform-object-rest-spread": "^6.26.0",
     "babel-preset-react": "^6.5.0",
     "webpack": "^3.8.1",
-    "webpack-dev-server": "^2.4.1"
+    "webpack-dev-server": "^3.10.3"
   },
   "dependencies": {
     "immutable": "^3.8.1",