Add inputs.nixpkgs.follows to rust-overlay in flake.nix (#1729)

* add `inputs.nixpkgs.follows` to `rust-overlay`

* Update flake.lock

Author: oati

flake.lock

@@ -3,7 +3,10 @@
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
-    rust-overlay.url = "github:oxalica/rust-overlay";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
     nixCargoIntegration = {
       url = "github:yusdacra/nix-cargo-integration";
       inputs.nixpkgs.follows = "nixpkgs";