GitHub Actions unit tests: add workaround for setup.py-compiled lxml …

…in combination with macos-11 (20221002.2) runner

.github/workflows/unittests.yaml

@@ -19,13 +19,21 @@ jobs:
             python-version: "3.11.0-rc.1"
           - os: windows-latest
             python-version: "3.11.0-rc.1"
+        include:
+          - os: macos-latest
+            python-version: "3.10"
+            lxml-binary-wheel-workaround: true
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v3
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
+      # 2022-10-10: setup.py-compiled lxml fails to parse test_wild_mode.testhtml on macos-11 (20221002.2) runner
+      - name: Workaround: force installation of binary wheel variant of lxml
+        if: ${{ lxml-binary-wheel-workaround }}
+        run: pip install --only-binary=lxml lxml
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip