Update core-js to the latest version 🚀 (#1518)

* chore(package): update core-js to version 3.6.5

* chore(package): update lockfile package-lock.json

Co-authored-by: greenkeeper[bot] <23040076+greenkeeper[bot]@users.noreply.github.com>

Author: greenkeeper[bot]

package-lock.json

@@ -82,7 +82,7 @@
     "babel-eslint": "10.1.0",
     "babel-loader": "8.1.0",
     "babel-plugin-transform-object-rest-spread": "6.26.0",
-    "core-js": "3.4.4",
+    "core-js": "3.6.5",
     "cross-env": "7.0.2",
     "css-loader": "3.5.1",
     "eslint": "6.8.0",