Github testing (orest-d#30)

Create pythonapp.yml
Closes orest-d#20

.github/workflows/pythonapp.yml

@@ -0,0 +1,28 @@
+name: tests
+
+on: [push, pull_request]
+
+jobs:
+  tests:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python 3.8
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.8
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install poetry
+        poetry -V
+        poetry install
+    - name: Test with pytest
+      run: |
+        poetry run pytest --cov=py
+    - name: Check code style
+      run: |
+        poetry run black --check src
+        poetry run black --check tests