ci: just use kunzen key

.github/workflows/check.yaml

@@ -17,12 +17,11 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
+      # Get access to kunzen
       - name: Setup SSH
         uses: webfactory/ssh-agent@v0.9.0
         with:
-          ssh-private-key: |
-            ${{ secrets.OOKNET_DEPLOY_KEY }}
-            ${{ secrets.KUNZEN_DEPLOY_KEY }}
+          ssh-private-key: ${{ secrets.KUNZEN_DEPLOY_KEY }}
 
       - name: Setup Nix
         uses: DeterminateSystems/nix-installer-action@main