nix-direnv: rm enableFlakes and pass nixUnstable

>        Failed assertions:
       - The option definition `programs.direnv.nix-direnv.enableFlakes' in `/nix/store/pv3vi4n7x83r4sc3ljqdgg9qifr4n5gp-source/users/profiles/direnv' no longer has any effect; please remove it.
       Flake support is now always enabled.

overlays/overrides.nix

@@ -15,6 +15,8 @@ channels: final: prev: {
     deploy-rs
     ;
 
+  # nix is set to 2.3 in 21.11
+  nix-direnv = prev.nix-direnv.override { nix = prev.nixUnstable; };
 
   haskellPackages = prev.haskellPackages.override
     (old: {

overlays/various-flake-fixes.nix

@@ -1,11 +0,0 @@
-final: prev: {
-  # Since: https://github.com/NixOS/nixpkgs/pull/126137
-  nix-direnv =
-    if builtins.hasAttr "enableFlakes" prev.nix-direnv.override.__functionArgs
-    then
-      prev.nix-direnv.override
-        {
-          enableFlakes = true;
-        }
-    else prev.nix-direnv;
-}

users/profiles/direnv/default.nix

@@ -3,7 +3,6 @@
     enable = true;
     nix-direnv = {
       enable = true;
-      enableFlakes = true;
     };
   };
 }