treewide: drop 25.05 compat code

apple/t2/default.nix

@@ -7,7 +7,6 @@
 
 let
   inherit (lib) types;
-  nixosVersion = lib.versions.majorMinor lib.version;
 
   audioFiles = pkgs.fetchFromGitHub {
     owner = "kekrby";
@@ -106,16 +105,9 @@ in
       powerManagement.enable = true;
     }
 
-    (
-      if lib.versionAtLeast nixosVersion "25.05" then
     {
       services.pulseaudio.package = overrideAudioFiles pkgs.pulseaudio "src/modules/";
     }
-      else
-        {
-          hardware.pulseaudio.package = overrideAudioFiles pkgs.pulseaudio "src/modules/";
-        }
-    )
 
     (lib.mkIf t2Cfg.enableIGPU {
       # Enable the iGPU by default if present

lenovo/thinkpad/z/gen2/z13/default.nix

@@ -1,4 +1,4 @@
-{ pkgs, lib, ... }:
+{ pkgs, ... }:
 
 {
   imports = [
@@ -14,8 +14,7 @@
         path = "${pkgs.modemmanager}/share/ModemManager/fcc-unlock.available.d/${id}";
       };
     in
-    if lib.versionOlder lib.version "25.05pre" then
-      { networkmanager.fccUnlockScripts = [ fcc_unlock_script ]; }
-    else
-      { modemmanager.fccUnlockScripts = [ fcc_unlock_script ]; };
+    {
+      modemmanager.fccUnlockScripts = [ fcc_unlock_script ];
+    };
 }

purism/librem/5r4/audio.nix

@@ -19,17 +19,6 @@
           '';
         };
       in
-      if lib.versionOlder (lib.versions.majorMinor lib.version) "25.05" then
-        {
-          assertions = [
-            {
-              assertion = config.hardware.pulseaudio.enable;
-              message = "Call audio on Librem5 requires pulse audio to be enabled through `hardware.pulseaudio.enable`.";
-            }
-          ];
-          hardware.pulseaudio = paConfig;
-        }
-      else
       {
         assertions = [
           {