Upgrade actions core and actions github packages (#649)

* Bump the dependencies group with 2 updates

Bumps the dependencies group with 2 updates: [@actions/core](https://github.com/actions/toolkit/tree/HEAD/packages/core) and [@actions/github](https://github.com/actions/toolkit/tree/HEAD/packages/github).

Updates `@actions/core` from 1.10.0 to 1.11.1
- [Changelog](https://github.com/actions/toolkit/blob/main/packages/core/RELEASES.md)
- [Commits](https://github.com/actions/toolkit/commits/HEAD/packages/core)

Updates `@actions/github` from 5.1.1 to 6.0.0
- [Changelog](https://github.com/actions/toolkit/blob/main/packages/github/RELEASES.md)
- [Commits](https://github.com/actions/toolkit/commits/HEAD/packages/github)

* bug: Use fetch request for mocked tests

Author: truggeri