chore(package): update karma-webpack to version 4.0.2

Closes #55

Author: greenkeeper[bot]

Diff for: package.json

@@ -26,7 +26,7 @@
     "karma": "^4.1.0",
     "karma-chrome-launcher": "^2.2.0",
     "karma-jasmine": "^2.0.1",
-    "karma-webpack": "^3.0.5",
+    "karma-webpack": "^4.0.2",
     "mini-css-extract-plugin": "^0.6.0",
     "ng-annotate-loader": "0.6.1",
     "ng-annotate-patched": "1.9.0",