update webpack version

Author: ajpal

package.json

@@ -38,8 +38,8 @@
     "file-loader": "^1.1.11",
     "html-webpack-plugin": "^3.2.0",
     "jest": "^22.1.3",
-    "webpack": "^4.8.1",
-    "webpack-cli": "^2.1.3"
+    "webpack": "^4.20.2",
+    "webpack-cli": "^3.1.1"
   },
   "jest": {
     "coverageDirectory": "./coverage/",