chore(deps): update cachix/install-nix-action digest to 7ab6e7f

Author: renovate[bot]

.github/workflows/ci.yml

@@ -82,7 +82,7 @@ jobs:
         with:
           fetch-depth: 0
 
-      - uses: cachix/install-nix-action@9280e7aca88deada44c930f1e2c78e21c3ae3edd # v31
+      - uses: cachix/install-nix-action@7ab6e7fd29da88e74b1e314a4ae9ac6b5cda3801 # v31
         with:
           nix_path: nixpkgs=channel:nixos-unstable-small
 
@@ -120,7 +120,7 @@ jobs:
           token: ${{ steps.generate_token.outputs.token }}
           persist-credentials: false
 
-      - uses: cachix/install-nix-action@9280e7aca88deada44c930f1e2c78e21c3ae3edd # v31
+      - uses: cachix/install-nix-action@7ab6e7fd29da88e74b1e314a4ae9ac6b5cda3801 # v31
         with:
           nix_path: nixpkgs=channel:nixos-unstable-small