update nix flake to support more platforms

flake.lock

@@ -1,5 +1,23 @@
 {
   "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1694529238,
+        "narHash": "sha256-zsNZZGTGnMOf9YpHKJqMSsa0dXbfmxeoJ7xHlrt+xmY=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "ff7b65b44d01cf9ba6a71320833626af21126384",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1694553957,
@@ -18,8 +36,24 @@
     },
     "root": {
       "inputs": {
+        "flake-utils": "flake-utils",
         "nixpkgs": "nixpkgs"
       }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
     }
   },
   "root": "root",

flake.nix

@@ -5,14 +5,15 @@
 
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/release-23.05";
+    flake-utils.url = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs }:
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
     let
-    system = "x86_64-linux";
-    pkgs = nixpkgs.legacyPackages.${system};
+      pkgs = import nixpkgs { inherit system; };
     in {
-    packages.${system}.default = pkgs.stdenv.mkDerivation {
+      packages.default = pkgs.stdenv.mkDerivation {
         pname = "tomato";
         version = "0.0.0";
 
@@ -91,9 +92,10 @@
         shellHook = "echo hello to tomato dev shell!";
       };
 
-    apps.${system}.default = {
-      program = "${self.packages.${system}.default}/bin/tomato";
+      apps.default = {
         type = "app";
-    };
+        program = "${self.packages.${system}.default}/bin/tomato";
       };
     }
+  );
+}