68763.Fixed

Fix mac_brew_pkg.list_pkgs crashing or producing incorrect results when Homebrew returns null values for cask metadata:

• When the installed version of a cask is null (e.g. Homebrew cannot determine the installed version), it is now reported as "unknown" instead of raising an error.
• When full_token is null, it is now filtered out so that None is never used as a package name key in the returned dictionary.