Merge pull request #60913 from nextcloud/backport/60896/stable34

[stable34] chore(deps): Update flake to NixOS 26.05

Author: AndyScherzinger

flake.lock

@@ -6,7 +6,7 @@
   };
 
   inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs/nixos-25.11";
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-26.05";
     flake-utils.url = "github:numtide/flake-utils";
 	phps = {
 	  url = "github:fossar/nix-phps";