Update react-router to the latest version 🚀 (#1022)

* chore(package): update react-router to version 4.4.0

* chore(package): update lockfile package-lock.json

Author: greenkeeper[bot]

package-lock.json

@@ -81,7 +81,7 @@
     "react-dnd": "7.3.2",
     "react-dnd-html5-backend": "7.2.0",
     "react-dom": "16.8.4",
-    "react-router": "4.3.1",
+    "react-router": "4.4.0",
     "react-router-dom": "4.3.1",
     "react-test-renderer": "16.8.4",
     "request": "2.87.0",