chore(deps): update cachix/install-nix-action action to v31.8.1

Author: renovate[bot]

.github/workflows/workflow.yaml

@@ -32,7 +32,7 @@ jobs:
         with:
           path: ~/repo-cache
           key: repo-cache-${{ runner.os }}-nixpkgs-${{ env.cache-version }}
-      - uses: cachix/install-nix-action@9280e7aca88deada44c930f1e2c78e21c3ae3edd # v31.7.0
+      - uses: cachix/install-nix-action@fd24c48048070c1be9acd18c9d369a83f0fe94d7 # v31.8.1
         with:
           nix_path: nixpkgs=./nixpkgs.nix
       - uses: tweag/configure-bazel-remote-cache-auth@144b0b915f13a418f5eafe2f68d19564ec136c62 # v0.1.1