Test caching

.forgejo/workflows/nix-check.yaml

@@ -4,8 +4,10 @@ jobs:
   print-content:
     runs-on: nix-runner
     steps:
-      - name: Dump Environment Variables
-        run: env | sort
+      - name: Test Nix Caching
+        run: |
+          # 1. Check time to 'fetch' a package the host already has
+          time nix-shell -p p7zip --run "7z --help"
 
       - name: Run hello
         run: /nix/store/aiblla3swfhcv348k8h10mnsg35wzvm6-hello-2.12.2/bin/hello