Simplified flake-utils example with uv2nix

[Fethbita]

I am trying to get a legacy Python project and have it run using uv2nix but I am failing to do so. When I try to add flake-utils to the uv2nix hello example, I get an error:

warning: input 'flake-utils' has an override for a non-existent input 'nixpkgs'
error:
       … in the left operand of the update (//) operator
         at /nix/store/fy1zkcaf993w05ylfqx93b27am49i27b-source/lib/customisation.nix:607:21:
          606|     let
          607|       self = f self // {
             |                     ^
          608|         newScope = scope: newScope (self // scope);

       … in the right operand of the update (//) operator
         at /nix/store/fy1zkcaf993w05ylfqx93b27am49i27b-source/lib/fixed-points.nix:327:12:
          326|       in
          327|       prev // overlay final prev
             |            ^
          328|     );

       (stack trace truncated; use '--show-trace' to show the full, detailed trace)

       error: opening file '/nix/store/y83rl0zns2fr12kfklpf3jq69nxbkahj-source/uv.lock': No such file or directory

I would like to ask if it is possible to add a simplified example in the repository with flake-utils that can be run on aarch64-darwin or others.

[adisbladis]

I think flake-utils should be avoided so I will not add any templates containing it.
It's better to use forAllSystems = lib.genAttrs lib.systems.flakeExposed; and avoid a dependency.