upgrade nixpkgs to NixOS 23.11

sp-modules/simple-nixos-mailserver/config.nix

@@ -1,4 +1,4 @@
-mailserverDate: { config, lib, ... }:
+{ config, lib, ... }:
 let
   sp = config.selfprivacy;
 in
@@ -66,11 +66,7 @@ lib.mkIf sp.modules.simple-nixos-mailserver.enable
       "admin@${sp.domain}" = "${sp.username}@${sp.domain}";
     };
 
-    certificateScheme =
-      if builtins.compareVersions mailserverDate "20230525011002"
-        >= 0
-      then "manual"
-      else 1;
+    certificateScheme = "manual";
     certificateFile = "/var/lib/acme/${sp.domain}/fullchain.pem";
     keyFile = "/var/lib/acme/${sp.domain}/key.pem";
 

sp-modules/simple-nixos-mailserver/flake.lock

@@ -42,11 +42,11 @@
         "utils": "utils"
       },
       "locked": {
-        "lastModified": 1687462267,
-        "narHash": "sha256-rNSputjn/0HEHHnsKfQ8mQVEPVchcBw7DsbND7Wg8dk=",
+        "lastModified": 1700085753,
+        "narHash": "sha256-qtib7f3eRwfaUF+VziJXiBcZFqpHCAXS4HlrFsnzzl4=",
         "owner": "simple-nixos-mailserver",
         "repo": "nixos-mailserver",
-        "rev": "24128c3052090311688b09a400aa408ba61c6ee5",
+        "rev": "008d78cc21959e33d0d31f375b88353a7d7121ae",
         "type": "gitlab"
       },
       "original": {

sp-modules/simple-nixos-mailserver/flake.nix

@@ -9,7 +9,7 @@
       imports = [
         mailserver.nixosModules.default
         ./options.nix
-        (import ./config.nix mailserver.lastModifiedDate)
+        ./config.nix
       ];
     };
     configPathsNeeded =