fix(package): update react-dom to version 16.13.0

Closes #124

Author: greenkeeper[bot]

package.json

@@ -17,7 +17,7 @@
     "gsap": "^1.18.2",
     "meteor-node-stubs": "^0.4.1",
     "react": "^16.13.0",
-    "react-dom": "^15.3.0",
+    "react-dom": "^16.13.0",
     "react-mixin": "^5.0.0",
     "scrollmagic": "2.0.5"
   }