Follow upstream devshell with nixUnstable, important fixes

for docker needed, see:

https://github.com/NixOS/nix/issues/5777

https://github.com/NixOS/nix/pull/5787

shell/bud/default.nix

@@ -1,7 +1,7 @@
 { pkgs, lib, budUtils, ... }: {
   bud.cmds = with pkgs; {
     get = {
-      writer = budUtils.writeBashWithPaths [ nixFlakes git coreutils ];
+      writer = budUtils.writeBashWithPaths [ nixUnstable git coreutils ];
       synopsis = "get [DEST]";
       help = "Copy the desired template to DEST";
       script = ./get.bash;

shell/devos.nix

@@ -34,7 +34,7 @@ in
   '');
 
   commands = with pkgs; [
-    (devos nixFlakes)
+    (devos nixUnstable)
     (devos agenix)
     {
       category = "devos";