fix(package): update mobx-react to version 6.1.3

Closes #48

Author: greenkeeper[bot]

package.json

@@ -22,7 +22,7 @@
     "lodash.startcase": "^4.4.0",
     "lodash.uniqueid": "^4.0.1",
     "mobx": "^5.8.0",
-    "mobx-react": "^5.4.3",
+    "mobx-react": "^6.1.3",
     "phaser": "^3.15.1",
     "react": "latest",
     "react-color": "^2.14.1",