use actions/deploy-pages

.github/workflows/github-pages.yml

@@ -7,6 +7,10 @@ on:
 jobs:
   main:
     if: github.event.workflow_run.conclusion == 'success'
+    permissions:
+      pages: write
+      id-token: write
+    environment: github-pages
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
@@ -18,11 +22,6 @@ jobs:
         with:
           path: ${{ steps.brew_cache.outputs.dir }}
           key: brew-v3
-      - name: Git config
-        run: |
-          git config user.name bot
-          git config user.email bot@example
-          git subtree add --prefix book origin gh-pages
       - name: Build assets
         run: |
           yarn install
@@ -31,9 +30,7 @@ jobs:
         run: |
           brew bundle
           mdbook build
-      - name: Publish
-        run: |
-          git add -f book
-          if git commit -m update; then
-            git subtree push --prefix book origin gh-pages
-          fi
+      - uses: actions/upload-pages-artifact@v1
+        with:
+          path: book
+      - uses: actions/deploy-pages@v1