try actions/runner-images#709 workaround

Author: Yobmod

.github/workflows/pythonpackage.yml

@@ -28,6 +28,9 @@ jobs:
     - name: Install dependencies and prepare tests
       run: |
         set -x
+        sudo rm -rf "/usr/local/share/boost"
+        sudo rm -rf "$AGENT_TOOLSDIRECTORY"
+
         python -m pip install --upgrade pip setuptools wheel
         python --version; git --version
         git submodule update --init --recursive