Bump core-js from 3.11.1 to 3.12.0

Bumps [core-js](https://github.com/zloirock/core-js/tree/HEAD/packages/core-js) from 3.11.1 to 3.12.0.
- [Release notes](https://github.com/zloirock/core-js/releases)
- [Changelog](https://github.com/zloirock/core-js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/zloirock/core-js/commits/v3.12.0/packages/core-js)

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

package.json

@@ -16,7 +16,7 @@
     "braces": "^3.0.2",
     "browser-sync": "^2.26.14",
     "child_process": "^1.0.2",
-    "core-js": "^3.11.1",
+    "core-js": "^3.12.0",
     "del": "^6.0.0",
     "fancy-log": "^1.3.3",
     "fstream": "^1.0.12",