ci: repair build

Author: doyougnu

.github/workflows/deploy.yml

@@ -11,7 +11,7 @@ jobs:
     steps:
     - uses: actions/checkout@v3
     - uses: cachix/install-nix-action@v22
-    - run:  nix build
+    - run:  nix build -o _build
     - name: Deploy 🚀
       uses: JamesIves/github-pages-deploy-action@v4.2.2
       with: