ci: fix nightly_docs workflow, use org Github App

Author: notmandatory

.github/workflows/nightly_docs.yml

@@ -34,14 +34,10 @@ jobs:
     if: github.ref == 'refs/heads/master'
     needs: [build_docs]
     runs-on: ubuntu-latest
-    permissions:
-      contents: write
     steps:
       - name: Checkout `bitcoindevkit.org`
         uses: actions/checkout@v4
         with:
-          persist-credentials: false
-          ssh-key: ${{ secrets.DOCS_PUSH_SSH_KEY }}
           repository: bitcoindevkit/bitcoindevkit.org
           ref: master
       - name: Create directories
@@ -54,7 +50,12 @@ jobs:
           name: built-docs
           path: ./docs/.vuepress/public/docs-rs/bdk/nightly/latest
       - name: Configure git
-        run: git config user.email "github-actions@github.com" && git config user.name "github-actions"
+        run: |
+          git config user.name "github-actions"
+          git config user.email "github-actions@github.com"
+          git remote remove origin
+          git remote add origin https://x-access-token:${APP_TOKEN}@github.com/${GITHUB_ORG}/bitcoindevkit.org.git
+          git fetch origin
       - name: Commit
         continue-on-error: true         # If there's nothing to commit this step fails, but it's fine
         run: git add ./docs/.vuepress/public/docs-rs && git commit -m "Publish autogenerated nightly docs"