fix(package): update mobx-react to version 6.0.3

Closes #33

Author: greenkeeper[bot]

package.json

@@ -63,7 +63,7 @@
   },
   "dependencies": {
     "mobx": "^5.8.0",
-    "mobx-react": "^5.4.3",
+    "mobx-react": "^6.0.3",
     "react-dom": "^16.7.0",
     "react": "^16.7.0"
   },