feat: update flakes and fix dependencies with nixpkgs follows

flake.lock

@@ -2,11 +2,11 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1742422364,
-        "narHash": "sha256-mNqIplmEohk5jRkqYqG19GA8MbQ/D4gQSK0Mu4LvfRQ=",
+        "lastModified": 1754725699,
+        "narHash": "sha256-iAcj9T/Y+3DBy2J0N+yF9XQQQ8IEb5swLFzs23CdP88=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "a84ebe20c6bc2ecbcfb000a50776219f48d134cc",
+        "rev": "85dbfc7aaf52ecb755f87e577ddbe6dbbdbc1054",
         "type": "github"
       },
       "original": {
@@ -16,22 +16,6 @@
         "type": "github"
       }
     },
-    "nixpkgs_2": {
-      "locked": {
-        "lastModified": 1735554305,
-        "narHash": "sha256-zExSA1i/b+1NMRhGGLtNfFGXgLtgo+dcuzHzaWA6w3Q=",
-        "owner": "nixos",
-        "repo": "nixpkgs",
-        "rev": "0e82ab234249d8eee3e8c91437802b32c74bb3fd",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nixos",
-        "ref": "nixpkgs-unstable",
-        "repo": "nixpkgs",
-        "type": "github"
-      }
-    },
     "root": {
       "inputs": {
         "nixpkgs": "nixpkgs",
@@ -40,14 +24,16 @@
     },
     "treefmt-nix": {
       "inputs": {
-        "nixpkgs": "nixpkgs_2"
+        "nixpkgs": [
+          "nixpkgs"
+        ]
       },
       "locked": {
-        "lastModified": 1742370146,
-        "narHash": "sha256-XRE8hL4vKIQyVMDXykFh4ceo3KSpuJF3ts8GKwh5bIU=",
+        "lastModified": 1754847726,
+        "narHash": "sha256-2vX8QjO5lRsDbNYvN9hVHXLU6oMl+V/PsmIiJREG4rE=",
         "owner": "numtide",
         "repo": "treefmt-nix",
-        "rev": "adc195eef5da3606891cedf80c0d9ce2d3190808",
+        "rev": "7d81f6fb2e19bf84f1c65135d1060d829fae2408",
         "type": "github"
       },
       "original": {

flake.nix

@@ -3,7 +3,10 @@
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
-    treefmt-nix.url = "github:numtide/treefmt-nix";
+    treefmt-nix = {
+      url = "github:numtide/treefmt-nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
   outputs =