nix: Switch to nixfmt for formatting of Flake

Signed-off-by: Steffen Vogel <steffen.vogel@opal-rt.com>

flake.nix

@@ -8,23 +8,23 @@
     nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
   };
 
-  outputs = {
-    self,
-    flake-utils,
-    nixpkgs,
-  }:
-    flake-utils.lib.eachDefaultSystem
-    (
-      system: let
+  outputs =
+    {
+      self,
+      flake-utils,
+      nixpkgs,
+    }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
         pkgs = nixpkgs.legacyPackages.${system};
-      in rec {
+      in
+      rec {
         packages.gont = pkgs.buildGoModule {
           name = "gont";
           src = ./.;
           vendorHash = "sha256-QOh1jBR7FL/fKFmJv7wGxuCghRLR3DV/0TzXd+bUFP0=";
-          buildInputs = with pkgs; [
-            libpcap
-          ];
+          buildInputs = with pkgs; [ libpcap ];
           doCheck = false;
         };
 
@@ -38,12 +38,10 @@
             packages.gont
           ];
 
-          inputsFrom = [
-            packages.gont
-          ];
+          inputsFrom = [ packages.gont ];
         };
 
-        formatter = nixpkgs.alejandra;
+        formatter = nixpkgs.nixfmt-rfc-style;
       }
     );
 }