Bump react from 16.10.2 to 16.12.0 (#12573)

Bumps [react](https://github.com/facebook/react/tree/HEAD/packages/react) from 16.10.2 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

@@ -123,7 +123,7 @@
     "prop-types": "^15.5.10",
     "punycode": "^2.1.0",
     "rails-ujs": "^5.2.4",
-    "react": "^16.10.2",
+    "react": "^16.12.0",
     "react-dom": "^16.12.0",
     "react-hotkeys": "^1.1.4",
     "react-immutable-proptypes": "^2.1.0",

yarn.lock

@@ -8875,10 +8875,10 @@ react-transition-group@^2.2.1:
     prop-types "^15.6.2"
     react-lifecycles-compat "^3.0.4"
 
-react@^16.10.2:
-  version "16.10.2"
-  resolved "https://registry.yarnpkg.com/react/-/react-16.10.2.tgz#a5ede5cdd5c536f745173c8da47bda64797a4cf0"
-  integrity sha512-MFVIq0DpIhrHFyqLU0S3+4dIcBhhOvBE8bJ/5kHPVOVaGdo0KuiQzpcjCPsf585WvhypqtrMILyoE2th6dT+Lw==
+react@^16.12.0:
+  version "16.12.0"
+  resolved "https://registry.yarnpkg.com/react/-/react-16.12.0.tgz#0c0a9c6a142429e3614834d5a778e18aa78a0b83"
+  integrity sha512-fglqy3k5E+81pA8s+7K0/T3DBCF0ZDOher1elBFzF7O6arXJgzyu/FW+COxFvAWXJoJN9KIZbT2LXlukwphYTA==
   dependencies:
     loose-envify "^1.1.0"
     object-assign "^4.1.1"