Use default user name

Author: danieldk

.github/workflows/build.yaml

@@ -22,8 +22,6 @@ jobs:
         with:
           name: huggingface
         #    authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
-        env:
-          USER: github_runner
       - name: Check formatting
         run: nix fmt -- --ci
       - name: Build