add Python CI GH Action workflow

Author: chrissimpkins

.github/workflows/python-ci.yml

@@ -0,0 +1,28 @@
+name: Python CI
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        python-version: [3.6, 3.7, 3.8, 3.9]
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Display Python version & architecture
+        run: |
+          python -c "import sys; print(sys.version)"
+          python -c "import struct; print(struct.calcsize('P') * 8)"
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install tox tox-gh-actions
+      - name: Test with tox
+        run: tox