Add github workflow to test branches

.github/workflows/python-test.yml

@@ -0,0 +1,26 @@
+name: Test branches
+
+on:
+  push:
+    branches-ignore: 
+      - master
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python: [3.6, 3.7, 3.8]
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python }}
+      - name: Install Tox
+        run: pip install tox
+      - name: Run Tox
+        # Run tox using the version of Python in `PATH`
+        run: tox -e py