Update cachix/install-nix-action action to v31.9.1

Author: renovate[bot]

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
             system: aarch64-linux
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
-      - uses: cachix/install-nix-action@4e002c8ec80594ecd40e759629461e26c8abed15 # v31.9.0
+      - uses: cachix/install-nix-action@2126ae7fc54c9df00dd18f7f18754393182c73cd # v31.9.1
       - run: nix flake check -L --system ${{ matrix.runs-on.system }}
   publish:
     if: github.event_name == 'push'