🐛 GHA: Install possible lxml build requirements (if building from source)

.github/workflows/test.yml

@@ -39,6 +39,9 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v3
 
+      - name: Install possible lxml build requirements (if building from source)
+        run: sudo apt-get install -y libxml2-dev libxslt-dev python3-dev
+
       - name: Update pip
         run: python3 -m pip install -U pip
       - name: Install requirements*.txt