Add flake.nix

Signed-off-by: Oliver Davies <oliver@oliverdavies.uk>

go-api/flake.nix

@@ -0,0 +1,23 @@
+{
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+  outputs =
+    { nixpkgs, ... }:
+    let
+      system = "x86_64-linux";
+      pkgs = import nixpkgs { inherit system; };
+    in
+    {
+      devShells.${system}.default = pkgs.mkShell {
+        packages = with pkgs; [
+          curlMinimal
+          go
+          jq
+        ];
+
+        shellHook = ''
+          go version
+        '';
+      };
+    };
+}