wip: add echo output if no cache hit

.forgejo/workflows/check.yml

@@ -25,6 +25,7 @@ jobs:
           echo "hash=$(md5sum flake.lock | awk '{print $1}')" >> $GITHUB_OUTPUT
       - name: Restore and cache Nix store
         uses: https://github.com/nix-community/cache-nix-action@v4
+        id: nix-store-cache
         with:
           key: cache-x86_64-linux-nix-store-${{ steps.flake-lock-hash.outputs.hash }}
           restore-keys: |
@@ -37,6 +38,9 @@ jobs:
           purge-key: cache-x86_64-linux-nix-store-
           purge-created: true
           purge-created-max-age: 42
+      - name: echo if no cache hit
+        if: steps.nix-store-cache.outputs.cache-hit != 'true'
+        run: echo no cache hit
       - name: Prepare cachix
         uses: https://github.com/cachix/cachix-action@v12
         with: