Include repository security advisories

[lukasbestle]

See https://docs.github.com/en/rest/security-advisories/repository-advisories?apiVersion=2022-11-28#list-repository-security-advisories

This would make the backup more complete.

[josegonzalez]

This project is considered feature complete for the primary maintainer @josegonzalez. If you would like a bugfix or enhancement, pull requests are welcome. Feel free to contact the maintainer for consulting estimates if you'd like to sponsor the work instead.