Update dependency enzyme to v3

Author: renovate-bot

package.json

@@ -85,7 +85,7 @@
     "copy-webpack-plugin": "4.2.3",
     "cross-env": "4.0.0",
     "css-loader": "0.28.7",
-    "enzyme": "2.9.1",
+    "enzyme": "3.6.0",
     "eslint": "3.19.0",
     "eslint-config-airbnb": "14.1.0",
     "eslint-import-resolver-webpack": "0.8.3",