Use nix shell for building script in workflow

.github/workflows/generate-site.yaml

@@ -12,14 +12,12 @@ jobs:
         with:
           nix_path: nixpkgs=channel:nixos-unstable
       - name: Setup for static site generation
-        uses: workflow/nix-shell-action@v1
-        with:
-          packages: nodejs,coreutils
-          script: |
-            mv notebook/ site/public/
-            cd site
-            npm install
-            npm run build
+        run: |
+          nix shell nixpkgs#nodejs
+          mv notebook/ site/public/
+          cd site
+          npm install
+          npm run build
       - name: Deploy to GitHub Pages
         if: success()
         uses: crazy-max/ghaction-github-pages@v2