add r install

Author: poldrack

.github/workflows/build-book.yml

@@ -24,7 +24,12 @@ jobs:
         uses: actions/setup-python@v4
         with:
           python-version: '3.12'
-
+  
+      # we need R for the rpy2 examples
+      - uses: r-lib/actions/setup-r@v2
+        with:
+          r-version: '4.5.2' 
+      
       - name: Install dependencies
         run: |
           curl -LsSf https://astral.sh/uv/install.sh | sh
@@ -39,4 +44,4 @@ jobs:
         uses: peaceiris/actions-gh-pages@v3
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
-          publish_dir: ./book/_build/html
+          publish_dir: ./book/_build/html