use the latest Flake Checker from Nixpkgs instead

Author: franckrasolo

flake.nix

@@ -23,7 +23,7 @@
 
         shellHook = ''
           # health checks for Nix flake inputs
-          nix run "github:DeterminateSystems/flake-checker/v0.2.8"
+          nix run https://flakehub.com/f/NixOS/nixpkgs/0.1#flake-checker
         '';
       };
     });