ci-tools: add required (stateVersion)["https://nixos.org/manual/nixos/stable/options.html#opt-system.stateVersion"] (#2469)

Signed-off-by: leongross <leon.gross@9elements.com>

Author: leongross

ci-tools/host-runner/configuration.nix

@@ -69,6 +69,7 @@ in
   imports = [
     ./hardware-configuration.nix
   ];
+  system.stateVersion = "25.05";
 
   # Keep SD card from running out of room
   nix.gc.automatic = true;