Fix guide env

Author: LegNeato

.github/workflows/deploy_guide.yml

@@ -10,6 +10,9 @@ jobs:
     # Only run on the main repository, not on forks
     if: github.repository == 'rust-gpu/Rust-CUDA'
     runs-on: ubuntu-latest
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
     permissions:
       contents: write
       pages: write