switch nixpath back to strings because of nixos

only works as list of attrsets in darwin

modules/common/shell/nixpkgs.nix

@@ -77,7 +77,7 @@
   nix = {
 
     # Set channel to flake packages, used for nix-shell commands
-    nixPath = [{ nixpkgs = pkgs.path; }];
+    nixPath = [ "nixpkgs=${pkgs.path}" ];
 
     # Set registry to this flake's packages, used for nix X commands
     registry.nixpkgs.to = {