Update cachix/install-nix-action digest to 9280e7a

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/ci.yml

@@ -170,7 +170,7 @@ jobs:
         if: github.ref_type == 'tag'
 
       - name: Install Nix
-        uses: cachix/install-nix-action@c134e4c9e34bac6cab09cf239815f9339aaaf84e # v31
+        uses: cachix/install-nix-action@9280e7aca88deada44c930f1e2c78e21c3ae3edd # v31
         with:
           github_access_token: ${{ secrets.GITHUB_TOKEN }}
         if: github.ref_type == 'tag'