Test on Python 3.9. Skip 3.7 to avoid creating too many builds. Release on 3.9.

Author: jaraco

.github/workflows/main.yml

@@ -6,13 +6,13 @@ jobs:
   test:
     strategy:
       matrix:
-        python: [3.6, 3.7, 3.8]
+        python: [3.6, 3.8, 3.9]
         platform: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.platform }}
     steps:
       - uses: actions/checkout@v2
       - name: Setup Python
-        uses: actions/setup-python@v1
+        uses: actions/setup-python@v2
         with:
           python-version: ${{ matrix.python }}
       - name: Install tox
@@ -29,9 +29,9 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - name: Setup Python
-        uses: actions/setup-python@v1
+        uses: actions/setup-python@v2
         with:
-          python-version: 3.8
+          python-version: 3.9
       - name: Install tox
         run: |
           python -m pip install tox