fix(nixos): neovim as default editor instead of nano

sometimes it seems that the nixos default EDITOR env var bleeds into the
user env? I haven't get to properly debug it, but I imagine it comes
from /etc/profile

anyway,this makes sure to set neovim.

Signed-off-by: Carlos Alexandro Becker <caarlos0@users.noreply.github.com>

machines/shared.nix

@@ -105,11 +105,15 @@
     curl
     git
     jq
-    neovim
     unzip
     wget
   ];
 
+  programs.neovim = {
+    enable = true;
+    defaultEditor = true;
+  };
+
   programs.fish.enable = true;
 
   services.openssh.enable = true;