Bump react from 16.11.0 to 16.12.0

Bumps [react](https://github.com/facebook/react/tree/HEAD/packages/react) from 16.11.0 to 16.12.0.
- [Release notes](https://github.com/facebook/react/releases)
- [Changelog](https://github.com/facebook/react/blob/master/CHANGELOG.md)
- [Commits](https://github.com/facebook/react/commits/v16.12.0/packages/react)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -85,7 +85,7 @@
     "postcss-normalize": "8.0.1",
     "postcss-preset-env": "6.7.0",
     "postcss-safe-parser": "4.0.1",
-    "react": "^16.11.0",
+    "react": "^16.12.0",
     "react-app-polyfill": "^1.0.2",
     "react-dev-utils": "^9.0.3",
     "react-dom": "^16.12.0",