Fix lxml build error by installing system dependencies (#1901)

- Add step to install libxml2-dev and libxslt1-dev before Python dependencies
- Required for building lxml==5.3.0 from source
- Fixes 'Error: Please make sure the libxml2 and libxslt development packages are installed'

Author: mackowski

.github/workflows/build-and-deploy-website.yml

@@ -23,6 +23,8 @@ jobs:
       uses: actions/setup-python@v5
       with:
         python-version: '3.x'
+    - name: Install system dependencies for lxml
+      run: sudo apt-get update && sudo apt-get install -y libxml2-dev libxslt1-dev
     - name: Install Python dependencies
       run: make install-python-requirements
     - name: Run build script