Allow Flake inputs to accept boolean and integer attributes
Allow Flake inputs to accept boolean and integer attributes

I believe that this makes it possible to do things like
Git inputs with submodules, but it also likely applies
to other input types from libfetchers.

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