[CI] no cache for node_modules, upgrade nixos/nix to 2.24.8

.gitlab-ci.yml

 # Fixing the nixos image saves CI time so it doesn't have to pull new
 #image every time (nixos/nix updates quite often).
 # image: nixos/nix:latest
-image: nixos/nix:2.22.0
+image: nixos/nix:2.24.8
 
 #before_script:
   #- nix-env -iA nixpkgs.nix nixpkgs.cacert
@@ -27,7 +27,7 @@ compile:
   cache:
     paths:
       - /nix/store
-      - node_modules/
+      #- node_modules/
       - output/
       - .spago/