ci/actions: add python 3.9 to test matrix

.github/workflows/code-quality.yaml

@@ -16,6 +16,6 @@ jobs:
     name: Linting
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
-    - uses: actions/setup-python@v1
+    - uses: actions/checkout@v2
+    - uses: actions/setup-python@v2
     - uses: pre-commit/action@v2.0.0

.github/workflows/main.yml

@@ -22,12 +22,12 @@ jobs:
     strategy:
       matrix:
         os: [Ubuntu, MacOS, Windows]
-        python-version: [2.7, 3.5, 3.6, 3.7, 3.8]
+        python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9]
     steps:
       - uses: actions/checkout@v2
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v1
+        uses: actions/setup-python@v2
         with:
           python-version: ${{ matrix.python-version }}
 

.github/workflows/skip.yml

@@ -32,6 +32,6 @@ jobs:
     strategy:
       matrix:
         os: [Ubuntu, MacOS, Windows]
-        python-version: [2.7, 3.5, 3.6, 3.7, 3.8]
+        python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9]
     steps:
       - run: exit 0