trial at forcing pipx under python 3.8

Author: gfwilliams

.github/workflows/build.yml

@@ -96,6 +96,8 @@ jobs:
         BOARD: ${{ matrix.board }} 
         UPLOADTOKEN: ${{ secrets.UPLOADTOKEN }}  
       run: |
+        python3.8 -m pip install --user pipx # hack to ensure pipx runs in python 3.8
+        python3.8 -m pipx ensurepath
         source ./scripts/provision.sh  ${{ matrix.board }}
         make
         ./scripts/ci_upload.sh