use docker action for setting up python

.github/workflows/debian.yml

@@ -15,10 +15,16 @@ jobs:
           submodules: true
           fetch-depth: 1
 
+      - name: Set up Python
+        uses: actions/setup-python@v1
+        with:
+          python-version: 3.9
+          architecture: x64
+
       - name: Build Debian/Apt package
         run: |
-          sudo apt install -y debhelper dh-python python3-all
-          pip install --upgrade pip setuptools wheel stdeb
+          sudo apt install -y debhelper dh-python
+          pip3 install --upgrade pip setuptools wheel stdeb
           ./bin/build_deb.sh
 
       - name: Install archivebox from deb