fix(package): update react-router to version 5.2.0

Closes #40

Author: greenkeeper[bot]

package.json

@@ -9,7 +9,7 @@
   "dependencies": {
     "react": "^15.4.0",
     "react-dom": "^15.4.0",
-    "react-router": "^4.0.0",
+    "react-router": "^5.2.0",
     "react-router-dom": "^4.0.0"
   },
   "scripts": {