chore(package): update react-dom to version 16.8.6

Closes #1029

Author: greenkeeper[bot]

package.json

@@ -80,7 +80,7 @@
     "react": "16.8.6",
     "react-dnd": "7.4.3",
     "react-dnd-html5-backend": "7.4.0",
-    "react-dom": "16.8.4",
+    "react-dom": "16.8.6",
     "react-router": "4.4.0",
     "react-router-dom": "4.4.0",
     "react-test-renderer": "16.8.4",