chore(deps): update cachix/install-nix-action digest to 56a7bb7

Author: renovate[bot]

.github/workflows/ci.yaml

@@ -10,5 +10,5 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
-    - uses: cachix/install-nix-action@91a071959513ca103b54280ac0bef5b825791d4d # v31
+    - uses: cachix/install-nix-action@56a7bb7b56d9a92d4fd1bc05758de7eea4a370a8 # v31
     - run: ./ci.sh