Use Python 3.9 as a base for actions

Signed-off-by: Philippe Ombredanne <pombredanne@nexb.com>

Author: pombredanne

.github/workflows/docs-ci.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        python-version: [3.7]
+        python-version: [3.9]
 
     steps:
       - name: Checkout code

.github/workflows/pypi-release.yml

@@ -13,7 +13,7 @@ jobs:
      - name: Set up Python
        uses: actions/setup-python@v1
        with:
-         python-version: 3.8
+         python-version: 3.9
      - name: Install pypa/build
        run: python -m pip install build --user
      - name: Build a binary wheel and a source tarball