flake: improve src filtering for rust packages

Author: xanderio

flake.lock

@@ -5,10 +5,7 @@
       url = "github:ipetkov/crane";
       inputs.nixpkgs.follows = "nixpkgs";
     };
-    gitignore = {
-      url = "github:hercules-ci/gitignore.nix";
-      inputs.nixpkgs.follows = "nixpkgs";
-    };
+    nix-filter.url = "github:numtide/nix-filter";
     fenix = {
       url = "github:nix-community/fenix";
       inputs.nixpkgs.follows = "nixpkgs";

flake.nix

@@ -5,7 +5,17 @@
       craneLib = inputs.crane.lib.${system}.overrideToolchain rustToolchain.toolchain;
       cargoArtifacts = craneLib.buildDepsOnly commonArgs;
       commonArgs = {
-        src = inputs.gitignore.lib.gitignoreSource ./..;
+        src = inputs.nix-filter.lib.filter {
+          root = ./..;
+          include = [
+            "nxy-common"
+            "nxy-cli"
+            "nxy-agent"
+            "nxy-server"
+            "Cargo.toml"
+            "Cargo.lock"
+          ];
+        };
 
         # enable unstable tokio `tracing` feature
         RUSTFLAGS = "--cfg tokio_unstable";