Update to nixos 23.05

- Update using patch notes
- Remove etherpad which didn't work
- Remove code-server which depended on deprecated nodejs versions and was unused
- Remove pkgs-unstable
- Update nodejs to nodejs-20
diff --git a/default/configuration.nix b/default/configuration.nix
index 3b8888e..0ccf399 100644
--- a/default/configuration.nix
+++ b/default/configuration.nix
@@ -129,12 +129,8 @@
 
   nix.settings.experimental-features = [ "nix-command" "flakes" ];
 
-  # Enable the OpenSSH daemon.
-  services.openssh.enable = true;
-  services.openssh.passwordAuthentication = false;
-
   # Open ports in the firewall.
-  networking.firewall.allowedTCPPorts = [ 22 80 443 25 465 587 110 995 143 993 ];
+  networking.firewall.allowedTCPPorts = [ 80 443 25 465 587 110 995 143 993 ];
   # networking.firewall.allowedUDPPorts = [ ... ];
   # Or disable the firewall altogether.
   networking.firewall.enable = true;