added github workflow

.github/workflows/ci.yml

@@ -0,0 +1,16 @@
+name: ci
+on: push
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ['3.5', '3.8', '3.9', 'pypy-3.9']
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - run: pip install . && pip install -r dev-requirements.txt
+      - run: pytest