fix rust template

templates/rust/flake.nix

@@ -1,8 +1,8 @@
 {
-  description = "Rust-Nix";
+  description = "Rust-Hello";
 
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/unstable";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     rust-overlay = {
       url = "github:oxalica/rust-overlay";
       inputs.nixpkgs.follows = "nixpkgs";
@@ -32,7 +32,7 @@
         # Use rust-bin to generate the toolchain from rust-toolchain.toml
         rust-toolchain = pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
 
-        buildRustCrateForPkgs = pkgs:
+        buildRustCrateForPkgs = _:
           pkgs.buildRustCrate.override {
             rustc = rust-toolchain; # Use rustc from toolchain
             cargo = rust-toolchain; # Use cargo from toolchain
@@ -52,6 +52,7 @@
           hello = cargoNix.rootCrate.build;
           default = hello;
         };
+
         devShell = pkgs.mkShell {
           buildInputs = [rust-toolchain];
         };