chore: use pre-commit treefmt integration

Author: mightyiam

modules/formatting.nix

@@ -4,10 +4,7 @@
     inputs.treefmt-nix.flakeModule
   ];
   perSystem = {
-    pre-commit.settings.hooks.nix-fmt = {
-      enable = true;
-      entry = "nix fmt -- --fail-on-change";
-    };
+    pre-commit.settings.hooks.treefmt.enable = true;
 
     treefmt = {
       projectRootFile = "flake.nix";