Bump core-js from 2.6.5 to 2.6.6
Bump core-js from 2.6.5 to 2.6.6

Bumps [core-js](https://github.com/zloirock/core-js) from 2.6.5 to 2.6.6.
- [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/compare/v2.6.5...v2.6.6)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
sue445/chrome-gitlab-notifier,sue445/chrome-gitlab-notifier