shell.nix: bump to current nixos-unstable (2025-10-23)

We can base the unstable haskell-ci on the default package set now which
saves a lot of compiling.

Author: sternenseemann

shell.nix

@@ -1,8 +1,8 @@
 { pkgs ?
     import (builtins.fetchTarball {
-      # nixos-unstable 2025-04-23
-      url = "https://github.com/nixos/nixpkgs/archive/96d30055a2215e5c5a545872376137a5d063e804.tar.gz";
-      sha256 = "0xvzkpgc8qy4q252c3x399c8ikrks970c877s4i7vppnhxp08p8n";
+      # nixos-unstable 2025-10-23
+      url = "https://github.com/nixos/nixpkgs/archive/01f116e4df6a15f4ccdffb1bcd41096869fb385c.tar.gz";
+      sha256 = "sha256-f/QCJM/YhrV/lavyCVz8iU3rlZun6d+dAiC3H+CDle4=";
     }) { }
 , ghcVersion ? pkgs.haskellPackages.ghc.version
   # Pass --arg minimal true to disable tools that are not strictly necessary
@@ -19,7 +19,7 @@ let
   haskellLib = pkgs.haskell.lib.compose;
 
   haskell-ci-pinned = lib.pipe
-    pkgs.haskell.packages.ghc9101.haskell-ci # compatible Cabal version by default
+    pkgs.haskellPackages.haskell-ci
     [
       (haskellLib.overrideSrc {
         version = "0-unstable-2025-03-30";