Fix warning on nix lazy-trees

`warning: Performing inefficient double copy of path '/home/artturin/nixgits/comma/' to the store. This can typically be avoided by rewriting an attribute like `src = ./.` to `src = builtins.path { path = ./.; name = "source"; }`.`

flake.nix

@@ -23,7 +23,10 @@
         in
         naersk-lib.buildPackage {
           pname = "comma";
-          root = ./.;
+          root = builtins.path {
+            name = "comma-source";
+            path = ./.;
+          };
           nativeBuildInputs = with pkgs; [ makeWrapper ];
           overrideMain = _: {
             postInstall = ''