updated nix to 25.05 and fixed setup.sh

Signed-off-by: Menno van Leeuwen <menno@vleeuwen.me>

setup.sh

@@ -4,7 +4,7 @@ set -euo pipefail
 IFS=$'\n\t'
 
 # Constants
-readonly NIXOS_RELEASE="24.11"                                      # Home Manager release version (Must match NixOS version)           
+readonly NIXOS_RELEASE="25.05"                                      # Home Manager release version (Must match NixOS version)           
 readonly GIT_REPO="https://git.mvl.sh/vleeuwenmenno/dotfiles.git"   # Dotfiles repository URL
 readonly DOTFILES_PATH="${HOME}/.dotfiles"                          # Dotfiles directory
 readonly SETUP_MARKER="${HOME}/.dotfiles-setup"                     # Setup marker file indicates setup has been run
@@ -221,7 +221,7 @@ install_nix() {
     fi
 
     log_info "Nix not detected, installing Nix..."
-    curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix -o install-nix.sh || \
+    curl --proto '=https' --tlsv1.2 -sSf -L "https://install.determinate.systems/nix?version=${NIXOS_RELEASE}" -o install-nix.sh || \
         die "Failed to download Nix installer"
     
     sh install-nix.sh install --no-confirm || die "Failed to install Nix"