Whitelist nixConfig.flake-registry
Whitelist nixConfig.flake-registry

flake-registry should be safe to set to an aribtrary value, since it
is identical to just setting `inputs`.

rycee/nix,rycee/nix,NixOS/nix,NixOS/nix,rycee/nix,rycee/nix,rycee/nix,NixOS/nix,NixOS/nix,NixOS/nix