ci(tools): update cachix/install-nix-action digest to 4e002c8

Author: renovate[bot]

.github/workflows/flake.yml

@@ -32,7 +32,7 @@ jobs:
           token: ${{ steps.token.outputs.token }}
 
       - name: Install nix
-        uses: cachix/install-nix-action@0b0e072294b088b73964f1d72dfdac0951439dbd # v31
+        uses: cachix/install-nix-action@4e002c8ec80594ecd40e759629461e26c8abed15 # v31
 
       - name: Update flake
         run: nix flake update