Revert to previous gh page version.

Author: morriscb

.github/workflows/deploy_book.yaml

@@ -5,14 +5,14 @@ on:
   push:
     branches:
     - main
-    - 'rc/*'
+    - rc/*
 
 # This job installs dependencies, builds the book, and pushes it to `gh-pages`
 jobs:
   deploy-book:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v4
 
     # Install dependencies
     - name: Set up Python 3.13
@@ -36,7 +36,7 @@ jobs:
 
     # Push the book's HTML to github-pages
     - name: GitHub Pages action
-      uses: peaceiris/actions-gh-pages@v4
+      uses: peaceiris/actions-gh-pages@v3.6.1
       with:
         github_token: ${{ secrets.GITHUB_TOKEN }}
         publish_dir: ./_build/html