Add the SSH key to the inventory step if needed

.github/workflows/workflow.yml

@@ -45,6 +45,10 @@ jobs:
         with:
           flakehub: true
       - uses: DeterminateSystems/magic-nix-cache-action@main
+      - uses: webfactory/ssh-agent@v0.9.0
+        if: ${{ inputs.enable-ssh-agent }}
+        with:
+          ssh-private-key: ${{ secrets.ssh-private-key }}
       - name: Inventory the flake for targeted systems
         id: inventory
         env: