build: Remove hashFiles from cache key

The azuwis/actions/nix will auto update cache if gcroots changed now

Author: azuwis

.github/workflows/build.yml

@@ -21,7 +21,6 @@ jobs:
     - uses: actions/checkout@v4
     - uses: azuwis/actions/nix@main
       with:
-        key: nix-${{ hashFiles('flake.*', 'yarn.lock') }}
         debug: ${{ github.event_name == 'workflow_dispatch' && inputs.debug }}
     - uses: cachix/cachix-action@v12
       with: