Revert "Setup python3"

This reverts commit 3487cd4.

Author: pan3793

.github/workflows/master.yml

@@ -126,10 +126,6 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v2
-      - name: Setup Python
-        uses: actions/setup-python@v2
-        with:
-          python-version: '3.x'
       # https://github.com/docker/build-push-action
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v1