Fix CI workflow to install mkdocs-material theme

.github/workflows/ci.yml

@@ -1,33 +1,36 @@
-name: Deploy MkDocs site to GitHub Pages
+name: Build and Deploy MkDocs Site
 
 on:
   push:
     branches:
-      - main  # or whatever branch you're using
+      - main
+  pull_request:
+    branches:
+      - main
 
 jobs:
   build:
     runs-on: ubuntu-latest
 
     steps:
-      - name: Checkout repository
+      - name: Checkout code
         uses: actions/checkout@v3
 
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: '3.9'
+          python-version: 3.9
 
-      - name: Install MkDocs and dependencies
+      - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install mkdocs
+          pip install mkdocs mkdocs-material
 
       - name: Build the site
         run: mkdocs build
 
       - name: Deploy to GitHub Pages
         uses: peaceiris/actions-gh-pages@v3
         with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
-          publish_dir: ./site
+          deploy_branch: gh-pages
+          folder: site