1. update `GHCup.Version` module. `ghcupURL` must only be updated if we change the `_toolRequirements` type or the JSON representation of it. The version of the json represents the change increments. `ghcUpVer` is the current application version.
2. Add/fix downloads to `GHCupDownloads` module, then run `ghcup-gen gen` to generate the new json and validate it via `ghcup-gen check`.