chore(package): update react-dom to version 16.12.0

Author: greenkeeper[bot]

package.json

@@ -4,7 +4,7 @@
   "dependencies": {
     "prop-types": "15.7.2",
     "react": "^16.12.0",
-    "react-dom": "^16.9.0",
+    "react-dom": "^16.12.0",
     "react-redux": "7.1.3",
     "react-router-dom": "5.1.0",
     "react-syntax-highlighter": "^10.3.5",