add an optional propperty (repo in source>kicad) for the build-configs json files, to allow setting files for an own fork repo

myFile.json > sources > kicad > repo this allows settings files to be created for your own forks.

Example file:

{
    "name:": "MyOwn KiCad 8.0 latest",
    "output_prefix": "kicad-",
    "package_version": "MyOwn-8.0-latest",
    "train": "nightly",
    "build_mode": "Release",
    "nsis": {
        "file": "install.nsi"
    },
    "sources": {
        "kicad": {
            "repo": "https://gitlab.com/myOwn/kicad.git",
            "ref": "branch/8.0-myOwn"
        },
        "symbols": {
            "ref": "tag/8.0.1"
        },
        "footprints": {
            "ref": "tag/8.0.1"
        },
        "3dmodels": {
            "ref": "tag/8.0.1"
        },
        "templates": {
            "ref": "tag/8.0.1"
        }
    },
    "vcpkg": {
        "manifest_mode": true
    }
}