fix(package): update core-js to version 3.2.1 (#574)

Author: greenkeeper[bot]

package.json

@@ -57,7 +57,7 @@
     "chalk": "^2.4.1",
     "compatible-debug": "^1.0.0",
     "cookie-parser": "^1.4.4",
-    "core-js": "3.2.0",
+    "core-js": "3.2.1",
     "cross-env": "^5.2.0",
     "draft-js": "^0.10.5",
     "draft-js-linkify-plugin": "^2.0.1",