build: update flake (#342)

* update feat
* change flake.nix

Author: George-Miao

flake.lock

@@ -5,10 +5,10 @@
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     rust-overlay.url = "github:oxalica/rust-overlay";
     flake-utils.url = "github:numtide/flake-utils";
+    rust-overlay.inputs.nixpkgs.follows = "nixpkgs";
   };
 
   outputs = {
-    self,
     nixpkgs,
     rust-overlay,
     flake-utils,