publisher-github: Allow to override asset with the same name

[mahnunchik]

Preflight Checklist

• [x] I have read the contribution documentation for this project.
• [x] I agree to follow the code of conduct that this project follows, as appropriate.
• [x] I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Problem Description

It would be nice to have an option to override existing asset on GitHub releases.

Proposed Solution

Remove existing asset here: https://github.com/electron-userland/electron-forge/blob/a2de8ea5ec7d66725cd20ef8dabbd727843b52a3/packages/publisher/github/src/PublisherGithub.ts#L97-L99

Alternatives Considered

Additional Information