Update deploy-docs.yml

.github/workflows/deploy-docs.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install mkdocs pymdown-extensions
+          pip install mkdocs pymdown-extensions mkdocs-material
 
       - name: Build MkDocs site
         run: mkdocs build --clean