ci(tools): update cachix/install-nix-action digest to 9280e7a

Author: renovate[bot]

.github/workflows/flake.yml

@@ -22,7 +22,7 @@ jobs:
 
       - name: Install nix
         id: nix
-        uses: cachix/install-nix-action@a809471b5c7c913aa67bec8f459a11a0decc3fce # v31
+        uses: cachix/install-nix-action@9280e7aca88deada44c930f1e2c78e21c3ae3edd # v31
 
       - name: Update flake
         id: flake