Update react monorepo to v16.13.0

Author: renovate-bot

realworld/frontend/package-lock.json

@@ -10,8 +10,8 @@
     "history": "4.10.1",
     "marked": "0.8.0",
     "prop-types": "15.7.2",
-    "react": "16.12.0",
-    "react-dom": "16.12.0",
+    "react": "16.13.0",
+    "react-dom": "16.13.0",
     "react-redux": "5.1.1",
     "react-router": "4.3.1",
     "react-router-dom": "4.3.1",