github: setup cachix binary cache

Signed-off-by: Stefan Kober <stefan.kober@cyberus-technology.de>
On-behalf-of: SAP stefan.kober@sap.com

Author: hertrste

.github/workflows/qa.yml

@@ -14,6 +14,10 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - uses: cachix/install-nix-action@v31
+      - uses: cachix/cachix-action@v17
+          with:
+          name: openstack-nix
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
       - name: Build
         run: |
           set -euxo pipefail