github-releases-repo is not passed to installers (homebrew)

When using `github-releases-repo` setting (e.g. to publish releases from a private to a public repo) the homebrew installer ends up still pointing to the private one.

To reproduce:

1. set `github-releases-repo` to a different repo
2. add a homebrew installer
3. cut a release and notice that even though releases are in the different repo the installer doesn't work as its using the main one

Start with the homebrew installer path and trace how the github-releases-repo setting is handled when a release is cut. Reproduce the issue with a different repository configured, then verify that the generated installer points to that repository rather than the main one.

Written by the indexing model from the issue text.