feat: adding nix flake for regen ledger

flake.nix

@@ -0,0 +1,41 @@
+{
+  description = "Regen Ledger development environment";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          buildInputs = with pkgs; [
+            # Specific Go version
+            go
+            gopls
+            golangci-lint
+
+            # Build tools
+            gnumake
+            gcc
+
+            # Development tools
+            delve
+            go-tools
+
+            # Optional but useful tools
+            jq
+            curl
+          ];
+
+          shellHook = ''
+            export GOPATH="$HOME/go"
+            export PATH="$GOPATH/bin:$PATH"
+          '';
+        };
+      });
+}

go.mod

@@ -156,7 +156,7 @@ require (
 	github.com/petermattis/goid v0.0.0-20230317030725-371a4b8eda08 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
-	github.com/prometheus/client_golang v1.16.0 // indirect
+	github.com/prometheus/client_golang v1.16.0
 	github.com/prometheus/client_model v0.3.0 // indirect
 	github.com/prometheus/common v0.42.0 // indirect
 	github.com/prometheus/procfs v0.10.1 // indirect