Flake: Use flake-utils instead of a self-written solution

flake.lock

@@ -1,5 +1,23 @@
 {
   "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1771369470,
@@ -18,8 +36,8 @@
     },
     "root": {
       "inputs": {
-        "nixpkgs": "nixpkgs",
-        "systems": "systems"
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
       }
     },
     "systems": {
@@ -32,8 +50,9 @@
         "type": "github"
       },
       "original": {
-        "id": "systems",
-        "type": "indirect"
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
       }
     }
   },